Narrated Abu Ghifar Al-Muthanna bin Sa'eed At-Ta'i:from Abu Tamimah al-Hujaimi from Jabir bin Sulaim who said: "I went to the Prophet (ﷺ) and I said: ''Alaikas-Salam (upon you be peace)' so he replied: 'Do not say "'Alaikas-Salam" rather say As-Salamu Alaik.'" And he mentioned the story in its entirety

English translation · Jami' at-Tirmidhi