سنن النسائي

It was narrated that Ibn Mas'ud said: "We used to pray with the Messenger of Allah (ﷺ) and we would say: "Peace (As-Salam) be upon Allah (SWT), peace be upon Jibril, peace be upon Mika'il.' The Messenger of Allah (ﷺ) said: 'Do not say "Peace (As-Salam) be upon Allah, for Allah is As-Salam." Rather say: "At-tahiyyatu lillahi was-salawatu wat-tayyibat, as-salamu 'alaika ayyuhan-Nabiyyu wa rahmatAllahi wa baraktuhu. As-salamu 'alaina wa 'ala 'ibad illahis-salihin, ashahdu an la illaha ill-Allah wa ashhadu anna Muhammadan 'abduhu wa rasuluhu (Allah compliments, prayers and pure words are due to Allah. Peace be upon you, O Prophet, and the mercy of Allah (SWT) and his blessings. Peace be upon us and upon the righteous slaves of Allah (SWT). I bear witness that none has the right to be worshipped except Allah and I bear witness that Muhammad is His slave and Messenger)."