Musannaf Ibn Abi Shayba 21:700

Ja'far ibn 'Awn narrated to us, from Mis'ar, from Dhakwan, from Abu Hurayrah, who said: The supplication of a Muslim is answered as long as he does not supplicate for an injustice, or for the severing of kinship ties, or says: "I have supplicated, but I have not been answered."