It wasnarrated from Abu Humaid As-Sa'di that they said:
"O MessengerofAllah! We have been commanded to send peace and blessings upon you.How should we send peace and blessings upon you?" He said: "Say:Allahumma salli 'ala Muhammadin wa azwajihi wa dhurriyatihi, kamasallayta 'ala Ibrahim; wa barik 'ala Muhammadin wa azwajihi wadhurriyatihi kama barakta 'ala ali Ibrahim fil-'alamin, innakaHamidumMajid (O Allah, send Your grace, honour and mercy uponMuhammad andhis wives and offspring, as You sent Your grace, honourand mercy uponIbrahim. O Allah, send Your blessings upon Muhammadand his wives andoffspring, as You sent Your blessings upon thefamily of Ibrahim amongthe nations, You are indeed Praiseworthy,Most Glorious)."
English reference: Vol. 1, Book 5, Hadith 905
Arabic reference: Book 5, Hadith 958