Moses prayed to God, entreating Him to reveal His Great and Holy Name unto him, so that he might call upon Him with it and secure the fulfilment of all his wishes. The Lord granted the prayer of Moses, and when the celestials knew that He had revealed the secret of the Ineffable Name, they cried out, "Blessed art Thou, O Lord, gracious Giver of knowledge!"
God is always regardful of the honor of the elders of a people, and He bade Moses assemble those of Israel and announce the approaching redemption to them. And as God knew beforehand how Pharaoh's obduracy would display itself, He made it known to Moses at once, lest he reproach God later with the Egyptian king's frowardness.