Yea, before the day was I am he. So the LXX; Jerome, and Stier; but most moderns translate, "Yea, from this time forth I am he" (setup. Ezekiel 48:35). Kay, however, thinks that the translation of the Authorized Version may stand.
Who shall let it? literally, as in Isaiah 14:27, who shall turn it back? i.e. "reverse it, undo it." Surely no one.