Abd al-Rahman bin Abd al-Qari (who had been appointed by Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) as official over the treasury) says: I heard Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) teaching the people the tashahhud in the prayer while he was on the minbar of the Messenger of Allah (peace and blessings be upon him). He was saying: "O people, when one of you sits in the final tashahhud of his prayer or in the middle tashahhud, let him say: 'Bismillahi khayril-asma' (In the name of Allah, which is the best of all names; all verbal, physical and financial acts of worship are for Allah alone)." O people: "I bear witness that there is no god but Allah, and I bear witness that Muhammad (peace and blessings be upon him) is His servant and Messenger." O people, the tashahhud comes before the salam: "Peace be upon you, O Prophet, and the mercy of Allah and His blessings. Peace be upon us and upon all the righteous servants of Allah." None of you should say: 'As-salamu 'ala Jibra'il, wa 'ala Mika'il, wa 'ala mala'ikatillah' (Peace be upon Jibril, peace be upon Mika'il, peace be upon the angels of Allah). When a person says 'As-salamu 'alayna wa 'ala 'ibadillahis-salihin' (Peace be upon us and upon the righteous servants of Allah), it is as though he has sent salam upon all the righteous servants of Allah, whether they are in the earth or in the heavens. Then after that let him give the salam.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2837