Where does “będący” come from?

będący (Polish) comes from Old Polish będący, from Proto-Slavic *bǫdǫťь.

Ancestry of “będący”, step by step

StepLanguageWordMeaning
1Old Polishbędącyfuture
2Proto-Slavic*bǫdǫťь—
Every word from Proto-Slavic *bǫdǫťь →Every word from Old Polish będący →