Where does “إِنْ” come from?

إِنْ (Arabic) comes from Proto-Semitic šim, from Proto-Uralic śüdäme — heart.

Ancestry of “إِنْ”, step by step

Step	Language	Word	Meaning
1	Proto-Semitic	šim	if
2	Proto-Uralic	śüdäme	heart

إِنْ — Etymology, Origin & Word History | Etymology Explorer