It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that he (peace and blessings be upon him) said: "A person's supplication continues to be answered so long as he does not supplicate for something sinful or for the severing of ties of kinship, and so long as he is not hasty." It was said to him (peace and blessings be upon him): O Messenger of Allah, what is being hasty (al-isti'jal)? He (peace and blessings be upon him) said: "The servant says: 'I supplicated a great deal, I supplicated a great deal, but my supplication was not answered.' Then he grows weary and abandons supplication."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة الاستسقاء / 6429