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.
أَتَيْتُ النَّبِيَّ ﷺ فَقُلْتُ عَلَيْكَ السَّلاَمُ فَقَالَ لاَ تَقُلْ عَلَيْكَ السَّلاَمُ وَلَكِنْ قُلِ السَّلاَمُ عَلَيْكَ وَذَكَرَ قِصَّةً طَوِيلَةً وَهَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ