The Messenger of Allah ﷺ said, "When any of you supplicates, let him not say, 'O Allah, forgive me if You wish,' or, 'O Allah, have mercy on me if You wish.' Rather, let him be firm in his request, for nothing can compel Him."In another narration, "And let him make his request great, for nothing that Allah grants is too great for Him."
أن رسول الله ﷺ قال: لا يقل أحدكم إذا دعا: اللهم اغفر لي إن شئت، اللهم ارحمني إن شئت، ليعزم المسألة؛ فإنه لا مكره له. وفي رواية: وليعظم الرغبة، فإن الله لا يتعاظمه شيء أعطاه.
Malik narrated it in Kitab Quran (28) from Abu Zinad, from Araj, from Abu Hurairah, who related it. Bukhari narrated it in Daawat (6339) through Malik's route with the same wording. Muslim narrated it in Zikr wal-Dua (2679: 8) through Ismail bin Jafar, from Ala (that is, Ibn Abdul-Rahman bin Yaqub Harqi), from his father, from Abu Hurairah with similar wording. The other narration is also his. He also narrated it (2679: 9) through Ata bin Mina, from Abu Hurairah with similar wording.