Where does “به” come from?

به (Arabic) comes from Arabic بِ, from Arabic بَاء.

Ancestry of “به”, step by step

به traces back through two separate lines of ancestry.

via Arabic بِ

StepLanguageWordMeaning
1Arabicبِby; with; in, with
2Arabicبَاء

via Arabic ـهُ

StepLanguageWordMeaning
1Arabicـهُits
Every word from Arabic بَاءEvery word from Arabic بِ