Sahih Bukhari
Oneness, Uniqueness of Allah (Tawheed)
Volume: 009 / Book Number: 093 / Hadith Number: 478
Narrated 'Abdullah:
We used to pray behind the Prophet and used to say: "As-Salamu 'Al-Allah. The Prophet said, "Allah himself is As-Salam (Name of Allah), so you should say: 'At-Tahiyatu lil-laihi was- sala-watu wat-taiyibatu, as-sallamu 'Alayka aiyuha-n-nabiyyu wa rahrmatu-l-lahi wa barak-atuhu, As-salamu 'alaina wa 'ala 'ibaldi-l-lahi as-salihin. Ashhadu an la ilaha il-lallah, wa ash-hadu anna Muhammadan 'abduhu wa rasuluhu."'