Sahih al-Bukhari, Hadith 7464 ⓘ
Narrated Anas: Allah's Messenger said, "Whenever anyone of you invoke Allah for something, he should be firm in his asking, and he should not say: 'If You wish, give me...' for none can compel Allah to do something against His Will."
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا عَبْدُ الْوَارِثِ، عَنْ عَبْدِ الْعَزِيزِ، عَنْ أَنَسٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِذَا دَعَوْتُمُ اللَّهَ فَاعْزِمُوا فِي الدُّعَاءِ، وَلاَ يَقُولَنَّ أَحَدُكُمْ إِنْ شِئْتَ فَأَعْطِنِي، فَإِنَّ اللَّهَ لاَ مُسْتَكْرِهَ لَهُ " .
also referenced under: Book 97, Hadith 90 (In-Book) & Volume 9, Book 93, Hadith 556 (USC-MSA)