Sunan Ibn Majah, Chapter: The Chapters of Establishing the Prayer and the Sunnah Regarding Them

"When we performed prayer with the Prophet (saw) we said: 'Peace be upon Allah from His slaves, peace be upon Jibrail and Mikail and so-and-so and so-and-so.' The Messenger of Allah (saw) heard us and said: 'Do not say peace (Salam) be upon Allah, for He is As-Salam. When you sit (during prayer) say: At-Tahiyyatu lillahi was-salawatu wat-tayyibatu; as-salamu 'alayka ayyuhan-Nabiyyu wa rahmatullahi wa barakatuhu; as-salamu 'alayna wa 'ala 'ibadillahis-salihin (All compliments, prayers and good words are due to Allah; peace be upon you, O Prophet, and the mercy of Allah and His blessings; peace be upon us and upon the righteous slaves of Allah)." For if you say that it will reach every righteous slave in the heavens and on earth. (Then say:) "Ashhadu an la ilaha illallah wa ashhadu anna Muhammad (SAW)an 'abduhu wa Rasuluhu (I bear witness that none has the right to be worshipped but Allah, and I bear witness that Muhammad (SAW) is His slave and Messenger)." (Sahih) (Another chain) with similar wording. (Another chain) that Abdullah bin Masud said: "The Prophet (saw) used to teach us the Tashahhud." And he mentioned similarly.