What is the ruling on a man who committed such acts? Are the parents or the mother sinful for leaving him in the nursery at that time? Is the mother rewarded for the traumas she endured? Will the child do the same thing when he grows up, out of revenge against his father?

If it is proven that the father is immoral and deviant and has harmed his son, he shall be disciplined and his custody revoked. Forcing parents to relinquish custody is not permissible, and there is no sin upon you for leaving the child if you were unaware of him being subjected to harm. Your patience and seeking reward will make you rewarded, and everything that befalls a Muslim in terms of harm, Allah expiates his sins thereby. There is no need to fear for the child if you raise him well and he becomes upright, and you have dealt with him kindly and urged him to honor his father, for Allah does not let the reward of those who do good go to waste.