كتاب الصلاة
4  
The Book of Prayers
(17)
Chapter: Sending Salat Upon The Prophet (saws) After The Tashah-hud
(17)
باب الصَّلاَةِ عَلَى النَّبِيِّ صلى الله عليه وسلم بَعْدَ التَّشَهُّدِ ‏
Sahih Muslim 405

Abdullah b. Zaid-he who was shown the call (for prayer in a dream) narrated it on the authority of Abu Mas'ud al-Ansari who said:

We were sitting in the company of Sa'id b. 'Ubida when the Messenger of Allah (ﷺ) came to us. Bashir b. S'ad said: Allah has commanded us to bless you. Messenger of Allah! But how should we bless you? He (the narrator) said: The Messenger of Allah (ﷺ) kept quiet (and we were so much perturbed over his silence) that we wished we had not asked him. The Messenger of Allah (ﷺ) then said: (For blessing me) say:" 0 Allah, bless Muhammad and the members of his household as Thou didst bless the mernbers of Ibrahim's household. Grant favours to Muhammad and the members of his household as Thou didst grant favours to the members of the household of Ibrahim in the world. Thou art indeed Praiseworthy and Glorious" ; and salutation as you know.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى التَّمِيمِيُّ، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ نُعَيْمِ بْنِ عَبْدِ اللَّهِ الْمُجْمِرِ، أَنَّ مُحَمَّدَ بْنَ عَبْدِ اللَّهِ بْنِ زَيْدٍ الأَنْصَارِيَّ، - وَعَبْدُ اللَّهِ بْنُ زَيْدٍ هُوَ الَّذِي كَانَ أُرِيَ النِّدَاءَ بِالصَّلاَةِ - أَخْبَرَهُ عَنْ أَبِي مَسْعُودٍ الأَنْصَارِيِّ قَالَ أَتَانَا رَسُولُ اللَّهِ صلى الله عليه وسلم وَنَحْنُ فِي مَجْلِسِ سَعْدِ بْنِ عُبَادَةَ فَقَالَ لَهُ بَشِيرُ بْنُ سَعْدٍ أَمَرَنَا اللَّهُ تَعَالَى أَنْ نُصَلِّيَ عَلَيْكَ يَا رَسُولَ اللَّهِ فَكَيْفَ نُصَلِّي عَلَيْكَ قَالَ فَسَكَتَ رَسُولُ اللَّهِ صلى الله عليه وسلم حَتَّى تَمَنَّيْنَا أَنَّهُ لَمْ يَسْأَلْهُ ثُمَّ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم قُولُوا ‏ "‏ اللَّهُمَّ صَلِّ عَلَى مُحَمَّدٍ وَعَلَى آلِ مُحَمَّدٍ كَمَا صَلَّيْتَ عَلَى آلِ إِبْرَاهِيمَ وَبَارِكْ عَلَى مُحَمَّدٍ وَعَلَى آلِ مُحَمَّدٍ كَمَا بَارَكْتَ عَلَى آلِ إِبْرَاهِيمَ فِي الْعَالَمِينَ إِنَّكَ حَمِيدٌ مَجِيدٌ ‏.‏ وَالسَّلاَمُ كَمَا قَدْ عَلِمْتُمْ ‏"‏ ‏.‏
Reference : Sahih Muslim 405
In-book reference : Book 4, Hadith 69
USC-MSA web (English) reference : Book 4, Hadith 803
  (deprecated numbering scheme)