Sunan an-Nasa'i 1293
It was narrated that abu Sa'eed Al-Khudri said:
"We said: 'O Messenger of Allah (ﷺ), we know how to send salams upon you, but how should we send salah upon you?' He said: 'Say: "Allahumma salli 'ala Muhammadin 'abdika wa rasulika kama salaita 'ala Ibrahim wa barik 'ala Muhammadin wa 'ala ali Muhammadin kama barakta 'ala Ibrahim (O Allah, send salah upon Muhammad, Your slave and Messenger , as You sent Salah upon Ibrahim, and send blessings upon Muhammad and upon the family of Muhammad as You sent blessings upon Ibrahim)."
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا بَكْرٌ، - وَهُوَ ابْنُ مُضَرَ - عَنِ ابْنِ الْهَادِ، عَنْ عَبْدِ اللَّهِ بْنِ خَبَّابٍ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ، قَالَ قُلْنَا يَا رَسُولَ اللَّهِ السَّلاَمُ عَلَيْكَ قَدْ عَرَفْنَاهُ فَكَيْفَ الصَّلاَةُ عَلَيْكَ قَالَ ‏
"‏ قُولُوا اللَّهُمَّ صَلِّ عَلَى مُحَمَّدٍ عَبْدِكَ وَرَسُولِكَ كَمَا صَلَّيْتَ عَلَى إِبْرَاهِيمَ وَبَارِكْ عَلَى مُحَمَّدٍ وَآلِ مُحَمَّدٍ كَمَا بَارَكْتَ عَلَى إِبْرَاهِيمَ ‏"‏ ‏.‏