John Calvin Commentary Exodus 6:10

"And Jehovah spake unto Moses, saying," — Exodus 6:10 (ASV)

And the Lord spoke to Moses. Moses more clearly explains how indulgently God endured the people's malicious rejection. Their just reward would have been for Him to allow them to perish many times over in their miseries, as they so obstinately rushed to their own ruin. Therefore, it is because of His extraordinary loving-kindness that He does not cease to help those who are determined to perish.

Moreover, we should note that Moses was strengthened by this new command, since he himself had been shaken by the people's despair. But it was no small sin to be so hardened and stupefied by misfortune as to reject the remedy offered to them. He might then reasonably conclude that he was to go no further, lest he foolishly expose himself to so many anxieties at his own great danger, and with no beneficial outcome. But God counters this temptation and commands him, nevertheless, to persevere in contending with Pharaoh's stubbornness.

But Moses's answer shows that this mission had again been entrusted to the holy man, after the people's anguish had closed the way for God’s grace. For when the people were first aroused by the initial message to a cheerful hope of deliverance, this happy beginning had encouraged Moses to apply extraordinary energy to carrying out his task. This energy might naturally have deserted him after the unsuccessful event that had now occurred, until he was inspired anew to persevere. He therefore asks to be dismissed, lest his labor be in vain. He argues from the lesser to the greater: since it would be much more difficult to influence Pharaoh's mind to relinquish his claims against his will than to persuade the afflicted people to receive the aid offered to them from on high.

But he had now learned from experience that the people’s hearts were like a door closed to God; why then should he try to move the exceedingly great rock from its place? Although it was not his intention to shake off the burden of the calling placed upon him, he still would have willingly withdrawn himself indirectly and turned his back on it. Thus we sometimes see the most dedicated of God’s servants beginning to lose heart in the midst of their course, especially when they encounter difficulties and stumble upon some path that is worse than they expected.

Therefore, we must more earnestly implore God that, amid the various trials with which we must contend, He may never deprive us of the help of His power, but rather continually inspire us with new strength in proportion to the intensity of our struggles. But what hope of deliverance now survived, when its minister was so disheartened and depressed and the people themselves had so openly despised it, if God had not accomplished all things by Himself? Nor is there any doubt that He wished to show, by this failure on men's part, that His own hand was sufficient for Him.

As for Moses calling himself of uncircumcised lips, I refer this to his stammering, which he had previously raised as an obstacle; although, if anyone prefers to understand it differently, I do not strongly object.