And he said, certainly I will be with thee,.... To encourage and strengthen him; to protect, defend, and preserve him, and to succeed and prosper him; to give him credit and respect with the people of Israel, and influence over Pharaoh to prevail upon him at length to let Israel go: and this shall be a token unto thee that I have sent thee; not the promise now made, nor the vision he had seen, but what follows: when thou hast brought forth the people out of Egypt, ye shall serve God upon this mountain: Mount Horeb or Sinai, as they did at the time of the giving of the law on it, when an altar was built upon a hill, and they offered burnt offerings and peace offerings, Exo 24:4 and this was a sign, "a posteriori", confirming the divine mission of Moses; and besides the promise of this, on which Moses might depend, being made by the Lord, assured him of success, that he should bring the children of Israel out of Egypt, since he and they would serve the Lord together at this mountain, and from whence he might conclude he had a mission and commission from God. Of a like kind is the sign or token given of the deliverance of Jerusalem from the army of Sennacherib, Isa 37:30.