What is the ruling on a father supplicating against his children with [the words] "May Allah not grant you success" or "May Allah not have mercy on you," and what should the children do in response to that?

A father is not permitted to supplicate against his child due to the prohibition from the Prophet, peace and blessings be upon him. A father's supplication against his son in a state of anger is often not answered, because the father does not genuinely intend the supplication, and this is from Allah's mercy towards His servants. Even if the father intends a supplication involving sin or severing ties of kinship, Allah does not answer him, especially if the children are dutiful and obedient. The hadith, "Three supplications are answered without a doubt: the supplication of a parent against his child," is specific to a disobedient child who persists in his disobedience.