By His mercy, Allaah does not answer the du’aa’ of parents against their children if it is at a time of anger, because Allaah says (interpretation of the meaning):
“And were Allaah to hasten for mankind the evil (they invoke for themselves and for their children, while in a state of anger) as He hastens for them the good (they invoke) then they would have been ruined. So We leave those who expect not their Meeting with Us, in their trespasses, wandering blindly in distraction” [Yoonus 10:11]
Ibn Katheer (may Allaah have mercy on him) said in his Tafseer (Exegesis) (2/554):
Here Allaah tells us of His forbearance and kindness towards His slaves, for He does not answer them when they pray against themselves or their wealth or their children at moments of anger. He knows that they do not really mean any ill, so He does not answer them out of kindness and mercy, as He does when they pray for themselves or their wealth or their children for goodness, blessing and growth. End quote.