It is narrated from Sayyiduna Abu Mas'ud Ansari (may Allah be pleased with him) that he states: The Messenger of Allah (peace and blessings be upon him) came to us while we were in the gathering of Sayyiduna Sa'd bin 'Ubadah (may Allah be pleased with him). Sayyiduna Bashir bin Sa'd (may Allah be pleased with him) submitted: O Messenger of Allah (peace and blessings be upon him)! Allah Almighty has commanded us to send blessings upon you; how should we send blessings upon you? The narrator says: The Messenger of Allah (peace and blessings be upon him) remained silent until we wished that we had not asked him. Then the Messenger of Allah (peace and blessings be upon him) said: "Say like this: «اللَّهُمَّصَلِّعَلَىمُحَمَّدٍوَعَلَىآلِمُحَمَّدٍكَمَاصَلَّيْتَعَلَىآلِإِبْرَاهِيمَوَبَارِكْعَلَىمُحَمَّدٍوَعَلَىآلِمُحَمَّدٍكَمَابَارَكْتَعَلَىآلِإِبْرَاهِيمَفِىالْعَالَمِينَإِنَّكَحَمِيدٌمَجِيدٌ» and peace as you have been taught."
Hadith Referenceالسنن المأثورة / باب ما جاء في الصلاة على الراحلة / 101
Hadith Takhrijصحیح مسلم، الصلاة، باب الصلاة على النبي بعد التشهد، رقم : 405۔