Akkadian

bâru - to stay firm, stable, in good health; to become certain, proved, certified (CAD B 125, AHw. 108)

No definitive etymology can be suggested. Has been usually identified with Hbr. bˀr (pi.) “to explain, to elucidate”, JPA bˀr (pa.) “to explain, to interpret”. Of interest is also Arb. bwr “to try, to prove by experiment or experience, to examine” (Lane 274).