Musnad Ahmad 26:467

'Abd al-Razzaq narrated to us, Sufyan informed us, from al-A'mash, and Mansur, and Husayn ibn 'Abd al-Rahman, and Abu Hashim, and Hammad, from Abu Wa'il, and from Abu Ishaq, from Abu al-Ahwas, and al-Aswad, from 'Abdullah, who said: We did not know what to say in the prayer. We used to say: "Peace be upon Allah, peace be upon Jibril, peace be upon Mika'il." He said: So the Prophet, peace and blessings of Allah be upon him, taught us and said: "Indeed, Allah is As-Salam (the Peace). So when you sit during two rak'ahs, say: 'At-tahiyyatu lillahi, was-salawatu wat-tayyibat. As-salamu 'alayka ayyuhan-nabiyyu wa rahmatullahi wa barakatuhu. As-salamu 'alayna wa 'ala 'ibadillahis-salihin' (All compliments, prayers, and pure words are for Allah. Peace be upon you, O Prophet, and the mercy of Allah and His blessings. Peace be upon us and upon the righteous servants of Allah)." Abu Wa'il said in his narration from 'Abdullah, from the Prophet, peace and blessings of Allah be upon him: "If you say it, it reaches every righteous servant in the heaven and on the earth." And Abu Ishaq said in the narration of 'Abdullah, from the Prophet, peace and blessings of Allah be upon him: "If you say it, it reaches every angel brought near, or prophet sent, or righteous servant. 'Ash-hadu an la ilaha illallah, wa ash-hadu anna Muhammadan 'abduhu wa rasuluh' (I bear witness that there is no god but Allah, and I bear witness that Muhammad is His servant and His messenger).'"