John Calvin Commentary Exodus 3:10

"Come now therefore, and I will send thee unto Pharaoh, that thou mayest bring forth my people the children of Israel out of Egypt." — Exodus 3:10 (ASV)

Come now therefore. After God had furnished his servant with promises to engage him more cheerfully in his work, he now adds commands and calls him to undertake the office to which he was appointed. And this is the best encouragement to duty, when God makes those who would otherwise be slow through doubt sure of good success. For although we must obey God’s plain commands without delay or hesitation, still he is willing to provide against our sluggishness by promising that our endeavors will not be vain or useless.

And certainly, it is a feeling naturally implanted in us all that we are excited into action by a confidence in good success. Therefore, although God sometimes, for the purpose of testing the obedience of his servants, deprives them of hope and commands them peremptorily to do this or that, still he more often cuts off hesitation by promising a successful outcome.

Thus, then, he now aroused Moses to perform his commands by setting the hope of deliverance before him. The copula must be understood as an illative particle, because the command and calling undoubtedly depend on the promise.