“The pronunciation of yhwh as Yahweh is a scholarly guess. Hebrew biblical mss were principally consonantal in spelling until well into the current era. The pronunciation of words was transmitted in a separate oral tradition. The Tetragrammaton was not pronounced at all, the word adonay, “my Lord,” being pronounced in its place; elohim, “God,” was substituted in cases of combination adonay yhwh (305 times; e.g. Gen 15:2). Though the consonants remained, the original pronunciation was eventually lost.” The Anchor Bible Dictionary (1992) Vol. VI, 1011.
–Henrik Bogdan, Western Esotericism and Rituals of Initiation, pg. 203