Abu Hurairah (May Allah be pleased with him) said:
The Messenger of Allah (ﷺ) said, "You must not supplicate: 'O Allah! forgive me if You wish; O Allah bestow mercy on me if You wish.' But beg from Allah with certitude for no one has the power to compel Allah."[Al-Bukhari and Muslim]Another narration of Muslim is: "A supplication should be made in full confidence and one should persistently express his desire (before Allah) in his supplication, for no bounty is too great for Allah to bestow (upon his slaves)."
App reference: Book 18, Hadith 233
Arabic/English book reference: Book 18, Hadith 1743