Here, I. God sends Moses the second time to Pharaoh (Exo 6:11) upon the same errand as before, to command him, at his peril, that he let the children of Israel go. Note, God repeats his precepts before he begins his punishments. Those that have often been called in vain to leave their sins must yet be called again and again, whether they will hear or whether they will forbear, Eze 3:11. God is said to hew sinners by his prophets (Hos 6:5), which denotes the repetition of the strokes. How often would I have gathered you?
II. Moses makes objections, as one discouraged, and willing to give up the cause, Exo 6:12. He pleads, 1. The unlikelihood of Pharaoh's hearing: "Behold the children of Israel have not hearkened unto me; they give no heed, no credit, to what I have said; how then can I expect that Pharaoh should hear me? If the anguish of their spirit makes them deaf to that which would compose and comfort them, much more will the anger of his spirit, his pride and insolence, make him deaf to that which will but exasperate and provoke him." If God's professing people hear not his messengers, how can it be thought that his professed enemy should? Note, The frowardness and untractableness of those that are called Christians greatly discourage ministers, and make them ready to despair of success in dealing with those that are atheistical and profane. We would be instrumental to unite Israelites, to refine and purify them, to comfort and pacify them; but, if they hearken not to us, how shall we prevail with those in whom we cannot pretend to such an interest? But with God all things are possible. 2. He pleads the unreadiness and infirmity of his own speaking: I am of uncircumcised lips; it is repeated, Exo 6:30. He was conscious to himself that he had not the gift of utterance, had no command of language; his talent did not lie that way. To this objection God had given a sufficient answer before, and therefore he ought not to have insisted upon it, for the sufficiency of grace can supply the defects of nature at any time. Note, Though our infirmities ought to humble us, yet they ought not to discourage us from doing our best in any service we have to do for God. His strength is made perfect in our weakness.
III. God again joins Aaron in commission with Moses, and puts an end to the dispute by interposing his own authority, and giving them both a solemn charge, upon their allegiance to their great Lord, to execute it with all possible expedition and fidelity. When Moses repeats his baffled arguments, he shall be argued with no longer, but God gives him a charge, and Aaron with him, both to the children of Israel and to Pharaoh, Exo 6:13. Note, God's authority is sufficient to answer all objections, and binds us to obedience, without murmuring or disputing, Phi 2:14. Moses himself has need to be charged, and so has Timothy, Ti1 6:13; Ti2 4:1.

But they hearkened not - Their bondage was become so extremely oppressive that they had lost all hope of ever being redeemed from it. After this verse the Samaritan adds, Let us alone, that we may serve the Egyptians: for it is better for us to serve the Egyptians than that we should die in the wilderness. This appears to be borrowed from Exo 14:12.
Anguish of spirit - קצר רוח kotzer ruach, shortness of spirit or breath. The words signify that their labor was so continual, and their bondage so cruel and oppressive, that they had scarcely time to breathe.

And Moses spake before the Lord,.... Who appeared in a visible form, and had spoke to him with an articulate voice, and before whom Moses stood, and made the following reply:

saying, behold, the children of Israel have not hearkened unto me; even though he brought a comfortable message to them from the Lord, and delivered many gracious promises of his to them, assuring them of deliverance out of Egypt, and of their possession of the land of Canaan:

how then shall Pharaoh hear me? making a demand upon him to part with a people, from whose labour he receives so much advantage, and has such an addition to his revenues, and who is a mighty king, and haughty monarch. And this is further enforced from his own weakness and unfitness to speak to Pharaoh:

who am of uncircumcised lips? had an impediment in his speech, could not speak freely and readily, but with difficulty; perhaps stammered, and so uttered superfluous syllables, repeated them before he could fully pronounce what he aimed at; or in other words, he was not eloquent, which was his old objection, and had been fully answered before: and by this it appears that there was no alteration in the speech of Moses since God spoke with him at Mount Horeb. Some think Moses expected to have had this impediment removed, and tacitly hints at it here, not being so well satisfied with Aaron's being joined with him as his mouth and spokesman, which seemed to carry in it some reflection upon him.

Moses spake so unto the children of Israel--The increased severities inflicted on the Israelites seem to have so entirely crushed their spirits, as well as irritated them, that they refused to listen to any more communications (Exo 14:12). Even the faith of Moses himself was faltering; and he would have abandoned the enterprise in despair had he not received a positive command from God to revisit the people without delay, and at the same time renew their demand on the king in a more decisive and peremptory tone.