The ruling on a father spending on his son and the reverse

Question:
May Allah reward you. Honorable Shaykh, this questioner says: What is the ruling on one who is short with his father in financial maintenance? Is it obligatory for the son to give his father from his salary? And if his salary is low, what does he do?

Answer:
Yes, you spend on him. Your salary is different. If the father does not have what to spend on himself, his maintenance is obligatory upon his son, just as the reverse is the case: if the son does not have what to spend on himself, it is obligatory for his father to spend on him what suffices him. This is an obligatory right, and it is not from charity or from the good deeds that are not obligatory. Rather, this is an obligatory right upon him from his salary and other than his salary, according to his ability. Yes.