Where does “assalamu 'alaikum” come from?

assalamu 'alaikum (Classical Malay) comes from Arabic اَلسَّلَام عَلَيْكُم — peace be upon you.

Ancestry of “assalamu 'alaikum”, step by step

Step	Language	Word	Meaning
1	Arabic	اَلسَّلَام عَلَيْكُم	peace be upon you

assalamu 'alaikum — Etymology, Origin & Word History | Etymology Explorer