Sefer Yetzirah

And when Abraham our father had formed and combined and investigated and reckoned and succeeded, then He-Qof-Bet-He, “The Holy One Blessed Be He” was revealed unto him, and unto Abraham He called this convocation: “Before I formed thee in the belly, I knew thee, and before thou left the womb, I sanctified thee, and I placed thee like a prophet amidst the nations.” And He made Abraham a beloved friend, and cut a covenant with him and his seed forever and ever.