Or HaChaim on Exodus 4:11/אור החיים על שמות ד׳:י״א

1 ויאמר ה׳ אליו מי שם פה, G'd said to him: "Who has given man a mouth, etc." G'd criticised Moses. He should have relied on the fact that the One who provides others with the ability to speak without impediment could also do the same for him. If G'd had failed to do so thus far, surely He must have had an adequate reason. If and when the need arose, G'd would surely remedy Moses' deformity. G'd responds with the words (verse 12) "and now go and I will be with you." He does not, however, assure Moses that He will cure him of his deformity. It is also possible that G'd only hinted to Moses that he should express repentance at his lack of trust that G'd would cure him.

2On the other hand, one may read meaning into what G'd did not say, i.e. that He did not instruct Moses how he could ensure that G'd would provide him with a healthy mouth, i.e. the equipment to impress people with his eloquence. G'd did not even hint that He is in the habit of rectifying defects such as speech defects that did not originate at birth. He declared that He provides the initial equipment, i.e. a sense of hearing, a sense of sight, etc. G'd did not refer to His taking remedial action in that regard. We are therefore at a loss as to what precisely G'd wanted to convey with His reply in verse 12.

3We must assume that in verse eleven G'd asserted His sovereignty inasmuch as He is the supreme intelligence having provided man with the organs necessary including a mouth, etc. Considering all this Moses should understand that if he was plagued by a deformity this was not accidental or an oversight but was part of an overall design by G'd who knows best. It is precisely because G'd had not seen fit to remedy Moses' deformity that the latter should have given Him credit for knowing what He was doing. Most of you are familiar with the aggadah reported in Shemot Rabbah 1,25 according to which the young Moses playfully removed Pharaoh's crown and placed it on his own head. Some of Pharaoh's advisers were alarmed at this and saw in it an omen of the future. They decided to test the child by placing two bowls in front of him. One contained glowing coals, the other glittering jewels. If Moses were to try and grab for the jewels he would be considered as potentially dangerous to Pharaoh and would be executed; if he grabbed for the glowing coals this would be seen as proof that his having removed Pharaoh's crown had only been a youthful prank by a child with average or below average intelligence. According to the aggadah, Moses was about to grab for the jewels when an angel guided his hands to the coals and he burned his mouth. As a result he was afflicted with a stammer. G'd hinted to Moses that unless He had seen some positive value in Moses' burning his mouth at that time He would not have allowed this to happen. G'd either allows something like this to happen because of something that will happen in the future, or it is retribution for some sin committed, something that could not apply in Moses' case. Rabbi Ami said in Shabbat 55 that no one is saddled with afflictions unless he has become guilty of some sin. If someone suffers from a stutter such as Moses, this too is considered an affliction. If so, it would have been incumbent for Moses to know the reason for his affliction and to remove its cause and then to pray to G'd concerning removal of his affliction. The fact that he did not do so indicates that his affliction had nothing to do with any sin of his. This is why G'd said to him: ועתה. This is to be understood as contradicting previously held convictions. In other words, there was no need for Moses to blame himself for his stutter and to take remedial action.

4As to his concern that Israel would not believe in his leadership because of his stammer, G'd told Him that He would assist him and teach him what to say.

5The words: לך ואנכי אהיה עם פיך "go and I shall be with your mouth," was an ironclad answer valid as long as Moses had not actually commenced his mission. As long as he had not yet become G'd's instrument there was no reason to cure his stammer. This is why G'd urged Moses by saying: "Go!" He implied that if Moses were to accept this mission he would notice that as soon as he began speaking his stammer would have disappeared. G'd said: והוריתיך אשר תדבר; there is a subtle difference between this and את אשר תדבר, which is what we would have expected. G'd did not tell Moses that He would teach him what to say, but He told Moses that He would demonstrate to him that he had developed fluency in speaking, etc. The reason G'd used the word: "I will teach you" instead of "I will show you," is that Moses was to notice that his cure was not something temporary, only for the benefit of fulfilling his mission, but that it would remain the norm from then on.