كتاب الإيمان
1  
The Book of Faith
(86)
Chapter: The Prophet (saws) will defer his supplication in order to intercede for his ummah
(86)
باب اخْتِبَاءِ النَّبِيِّ صلى الله عليه وسلم دَعْوَةَ الشَّفَاعَةِ لأُمَّتِهِ ‏‏
Sahih Muslim 199 b

Abu Huraira said:

The Messenger of Allah (ﷺ) said: Every Messenger is endowed with a prayer which is granted and by which he would (pray to his Lord) and it would he granted for him. I have, however, reserved my prayer for the intercession of my Ummab on the Day of Resurrection.
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا جَرِيرٌ، عَنْ عُمَارَةَ، - وَهُوَ ابْنُ الْقَعْقَاعِ - عَنْ أَبِي زُرْعَةَ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ لِكُلِّ نَبِيٍّ دَعْوَةٌ مُسْتَجَابَةٌ يَدْعُو بِهَا فَيُسْتَجَابُ لَهُ فَيُؤْتَاهَا وَإِنِّي اخْتَبَأْتُ دَعْوَتِي شَفَاعَةً لأُمَّتِي يَوْمَ الْقِيَامَةِ ‏"‏ ‏.‏
Reference : Sahih Muslim 199b
In-book reference : Book 1, Hadith 398
USC-MSA web (English) reference : Book 1, Hadith 390
  (deprecated numbering scheme)