“The supplication of one of you will be answered as long as he is not hasty, such that he says: ‘I supplicated and supplicated but I was not answered.’ So then he stops supplicating.”
~ Saheeh Muslim #2735
Shaykh Muhammad bin Saalih al-‘Uthaymeen (rahimahullaah) comments:
“And this from the ignorance of a person because Allaah, subhaanahu wa ta’aala, will not prevent you from what you made du’aa to Him for except for a wisdom or due to the presence of something that is preventing the du’aa from being answered.
So don’t despair and make du’aa as du’aa is worship, so why wouldn’t you do a lot of it? Do much of it and don’t have ill thoughts of Allaah, ‘azza wa jal, for indeed Allaah, ta’aala, is All-Wise.”