Sahih al-Bukhari, Volume 8, Book 75, Hadith 317 (USC-MSA) ⓘ
Narrated Abu Huraira: Allah's Messenger said, "For every prophet there is one (special invocation (that will not be rejected) with which he appeals (to Allah), and I want to keep such an invocation for interceding for my followers in the Hereafter."
حَدَّثَنَا إِسْمَاعِيلُ، قَالَ حَدَّثَنِي مَالِكٌ، عَنْ أَبِي الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " لِكُلِّ نَبِيٍّ دَعْوَةٌ يَدْعُو بِهَا، وَأُرِيدُ أَنْ أَخْتَبِئَ دَعْوَتِي شَفَاعَةً لأُمَّتِي فِي الآخِرَةِ " .
also referenced under: Book 80, Hadith 1 (In-Book) & Hadith 6304 (DarusSalam)
Narrated Anas: that the Prophet said, "For every prophet there is an invocation that surely will be responded by Allah," (or said), "For every prophet there was an invocation with which he appealed to Allah, and his invocation was accepted (in his lifetime), but I kept my (this special) invocation to intercede for my followers on the Day of Resurrection."
وَقَالَ لِي خَلِيفَةُ قَالَ مُعْتَمِرٌ سَمِعْتُ أَبِي، عَنْ أَنَسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " كُلُّ نَبِيٍّ سَأَلَ سُؤْلاً ـ أَوْ قَالَ لِكُلِّ نَبِيٍّ دَعْوَةٌ قَدْ دَعَا بِهَا ـ فَاسْتُجِيبَ، فَجَعَلْتُ دَعْوَتِي شَفَاعَةً لأُمَّتِي يَوْمَ الْقِيَامَةِ " .
also referenced under: Book 80, Hadith 2 (In-Book) & Hadith 6305 (DarusSalam)