Source: Tuhfah Al-Mawdud by Ibn Qayyim – P. 158-161 and P. 168-171
Allah Says in the Qur’an [meaning of which is], “O you who have believed, protect yourselves and your families from a Fire whose fuel is people and stones” [Qur’an 66:6]. Ali, may Allah be pleased with him, said, “Teach them [the religion] and teach them good manners.” Al-Hasan said, “Command them to obey Allah and teach them goodness.”
The Messenger of Allah (pbuh) is reported to have said, “Command your children to pray when they reach the age of seven. Spank them  for [not offering] it when they are ten and separate them in their beds ” [Abu Dawud].
The Prophet (pbuh) is reported to have said, “Inspire your children’s first words to be La ilaha illa Allah [there is no deity worthy of worship except Allah] and prompt them with it during death” [Al-Hakim]
The Messenger of Allah (pbuh) is reported to have said, “One of you teaching good manners to his child is better for him than giving half a sa’a in charity everyday to the poor” [Tabrani].
The Messenger of Allah (pbuh) was asked, “O’ Messenger of Allah, we know the right of the father but what is the right of the child?” He (pbuh) responded, “That he be given a good name and be taught good manners” [Bayhaqi]. Sufyan Al-Thawri said, “A person should compel his child to seek [knowledge of] hadith because he is responsible for him. Whoever wants the worldly life [through knowledge of hadith], then he will find it and whoever wants the afterlife, then he will find it.” Ibn Umar said, “Teach good manners to your child because you are responsible for him and he is responsible for being dutiful and obedient to you.”
Messenger of Allah (pbuh) is reported to have said, “Whoever has a child, then let him give him a good name and teach him good manners, then when he reaches puberty, he should get him married. If his child reaches puberty and he does not get him married and then this child commits a sin, then his sin is on his father” [Bayhiqi].
Al-Hasan was asked about the Qur’anic verse, “And those who say, “Our Lord, grant us from among our wives and offspring comfort to our eyes” [Qur’an 25:74], “What is meant by comfort to our eyes? Does it mean in this life or the afterlife?” Al-Hasan responded, “By Allah, it means in this life.” Then he was asked, “What is it?” He responded, “That Allah sees [His] slave’s wife, brother, or close relative being obedient to Allah. By Allah, there is nothing more beloved to a Muslim than to see [his] child, father, close relative, or brother being obedient to Allah.”
Messenger of Allah (pbuh) said, “Everyone of you is a guardian and is responsible for his charges: The ruler of the people is a guardian and is responsible for his subjects; a man is the guardian of his family (household) and is responsible for his subjects; a woman is the guardian of her husband’s home and of his children and is responsible for them; and the slave of a man is a guardian of his master’s property and is responsible for it. Surely, everyone of you is a guardian and responsible for his charges” [Bukhari].
Being Just Between Children in Giving Gifts is Among Their Rights
Messenger of Allah (pbuh) said, “Be just between your children, be just between your children, be just between your children” [Ahmad]. It is also reported that the wife of Bashir said to her husband, “Give my son a slave [as a gift] and make the Messenger of Allah (pbuh) a witness over it.” So Bashir came to the Messenger of Allah (pbuh) and said, “The daughter of so and so asked me to give her son my slave [as a gift] and make the Messenger of Allah a witness over it.” The Prophet (pbuh) asked, “Does he [the son] have brothers?” Bashir replied, “Yes.” Then the Prophet (pbuh) asked, “Have you given to all others as you have given to him?” Bashir replied, “No.” So the Prophet Muhammad (pbuh) said, “Then this is not correct. Verily, I only bear witness over that which is correct” [Muslim].
Nu’man b. Bashir reported that his father brought him to Allah’s Messenger (pbuh) and said, “I have donated this slave of mine to my son.” Allah’s Messenger (pbuh) said, “Have you donated to every one of your sons (a slave) like this?” He said, “No.” Thereupon Allah’s Messenger (pbuh) said, “Then take him back” [Muslim]. In another version of the hadith, it is reported that the Prophet (pbuh) said, “Fear Allah and be just between your children” [Muslim]. This command is a threat, therefore, such a gift is not permissible due to it being a form of injustice. The Messenger of Allah (pbuh) did not allow anyone to be a witness over such injustice including himself. This type of gift favoring is not correct and is opposite of justice.
It is strange to suggest that the Prophet Muhammad’s (pbuh) statement, “Be just between your children,” is not an obligation. It is an absolute command which he emphasized three times. Justice is obligatory in every circumstance and if a command is given in an absolute form, then it carries the ruling of obligation.
It is reported that a man was sitting with the Prophet (pbuh). Then the man’s son came to him so he kissed him and placed him in his lap. Then the man’s daughter came so he took her and made her sit beside him. The Prophet (pbuh) said to him, “Why can’t you be just between them?”[Bayhaqi]. The early generations (salaf) used to love being just between children.
Some of the people of knowledge said that Allah will ask the father about his child on the Day of Judgement before asking the child about his father. Just as the father has rights over his son, similarly, the son has rights over his father. As Allah said in the Qur’an [meaning of which is], “And We have enjoined on mankind to be good to his parents” [Qur’an 29:80]. And He [also] said [meaning of which is], “O you who have believed, protect yourselves and your families from a Fire whose fuel is people and stones” [Qur’an 66:6].
Advice of Allah to the fathers for their children preceded His advice to the children for their fathers. Allah said [meaning of which is], “Do not kill your children out of fear of poverty” [Qur’an 17:31]. The one who neglects teaching his child with what benefits him and leaves him in vain has harmed him. Most children only become corrupted because their fathers neglect them and abandon teaching them the obligatory and recommended [sunan] aspects of the religion. They waste their children’s childhood so that they [grow up to] not benefit themselves nor their fathers. Then in old age the father admonishes his child for being ungrateful so the child responds, “O’ My father, you were ungrateful to me when I was small, so I am ungrateful to you when you are old. You wasted me as a boy so I am wasting you as an old man.”
Accustoming Children to Good Habits From the Beginning
It is very important to take care of the child’s conduct and manners [early on] because the child grows up based on what the one who raised him accustomed him to in childhood. So if the child is made used to [too much] freedom, anger, stubbornness, hastiness, easily following desires, heedlessness, harshness, greed, etc., then it will become difficult for such a child to avoid these things in adulthood and such manners will become firm qualities and attributes of his personality. If he firmly avoided these things, then it would be good for him someday. This is why it is found that most people [who] are crooked in their manners [are so] because that’s the type of upbringing on which they were raised.
When a child matures, he must be kept away from bad company, such as that of filth, innovation, evil speech, [forbidden forms of] amusement, singing, and music. This is because when [a child] gets caught up [and used to] listening to such things, it becomes difficult to separate from them in adulthood. It will also be difficult [then] for the child’s guardian to deplete such things from him. Changing habits is from among the most difficult of tasks [because] its owner needs to renew [his] nature, which is very difficult.
The child’s guardian should [also] strongly prevent him from [always] taking from others. If the child becomes accustomed to this, then it will become part of his nature and he will grow up [always] taking and never giving. So whenever [the guardian] wants to give something [such as in charity], he should place it in the child’s hand to give it away so that the child can taste the sweetness of giving.
The child should also be prevented from lying and treacherous behavior. When such a path becomes easy, then it will ruin his happiness in this life and the afterlife and will prevent him from every type of good.
The child must be prevented from laziness, idleness, [excessive] fondness, and [excessive] rest. Rather, he should be the opposite of those things and his soul and body should be kept busy. Laziness and idleness have evil consequences and result in regret, whereas, hard work and fatigue have praiseworthy consequences either in this world, hereafter, or in between. Supremacy in the world and happiness in the hereafter cannot happen except through the bridge of fatigue. Yahya bin Abi Kathir said, “Knowledge is not obtained by resting the body [rather by] accustoming it to waking up at the end of the night, which is a time for dividing the booty and awards. Some will take a little, some will take a lot, and some will take nothing.” When a person is made accustomed to hard work as a child, it becomes easy as an adult.
The child should be made to avoid excessive eating, speaking, sleeping, and mixing with people. There is loss in excessively engaging in these behaviors and cause the slave to miss the good of this world and the hereafter. He should [also] be strongly prevented from harmful desires associated with the stomach and the private parts because if the means and paths to such things are made possible for the child, then it will [surely] corrupt him and will make it difficult afterwards to correct his behavior. How many fathers are there who have made their child miserable in this world and the next by neglecting him, not disciplining him, and assisting him with his lusts? And [such a father] claims to be honoring and being merciful towards him, while in reality, he is dishonoring, depriving and oppressing him. Therefore, he fails to benefit through his child and loses his portion in this world and the afterlife. When you come across children who are immoral/corrupt, then take a look at their fathers first.
Be cautious and keep away anything from the child that may remove his intellect, such as, intoxicants. And [also] be cautious of [bad] companionship whom you fear may corrupt him, his speech, or negatively influence him. All of this is destruction. When such things are made easy for the child, then his loss of shame [will also] become easy and [remember that] the cuckold does not enter paradise . How many corrupt children are there due to their fathers’ carelessness, disregard, and being lax [over their children’s] evils? Most fathers rely on their children more than a severe enemy relies on the enmity against his enemy but they perceive it not! But [yet] how many fathers deprive their child of the good of this world and the afterlife and destroy both? All of these are consequences of fathers who are careless regarding the rights of Allah, straying away from them and turning away from what Allah made obligatory for them of beneficial knowledge and righteous actions. They are deprived of benefiting from their children, who [in return] withhold good and benefit from them. This is the punishment of [such] fathers.
The child should be prevented from intoxicants, theft, and lying. If it’s a boy, then he should [also] be prevented from wearing silk because it is corruptive for him and feminish for his nature. Prophet (pbuh) said, “[Wearing] silk and gold are prohibited for the males of my nation but permissible for the females” [Nasa’i]. If the child is not responsible [due to young age], then his guardian is responsible to not allow [him] forbidden things, otherwise, he will become accustomed to them and find it difficult to give them up. This is the most correct of the scholarly statements. Those [scholars] who argue that it is not forbidden say so because they view the child as not responsible. So they do not prohibit him from wearing silk but this [opinion] is not correct. If the child is not responsible [yet], then he must be prepared for responsibility [of fulfilling the divine commands].
Prepare the Child Based on His Condition
If the child does what he is not prepared for, then he will not succeed in it and will miss out on what he is prepared for. Therefore, if you see in him good understanding, cognition, alertness, and memory, then these are good and acceptable signs of his disposition for knowledge. So inscribe in his heart [knowledge] while it is [still] free [from corruption] because he can handle it and settle it down in his heart and be purified with it. But if you see in the child the opposite of the previous case from all directions but he is good with horsemanship, riding, shooting, etc., and knowledge does not get through to him, then [it means] he was not created for it. Therefore, engage him in such activities and have him practice because it will benefit him and the Muslims. And if you see in a child opposite to that [as well], then [it means] he was not created for it. In such a case look for a craft for him in an industry that is permissible and beneficial to the people. All of this should be done after teaching him what is necessary for him in the religion .
 Does not mean physical abuse, which is forbidden in Islam.
 Meaning do not let them sleep together without some sort of barrier in between. This is regardless of whether they are of the same-sex or not. [Source]
 The Messenger of Allah (pbuh) said: “There are three at whom Allah will not look on the Day of Resurrection: The one who disobeys his parents, the woman who imitates men in her outward appearance, and the cuckold” [Nasa’i]
 Such as how to pray, fast, make wudu, forbidden things, etc.