Open thy mouth wide - Let thy desires be ever so extensive, I will gratify them if thou wilt be faithful to me. Thou shalt lack no manner of thing that is good.
I am the Lord thy God - See Exodus 20:2. The meaning is, “I am Yahweh, that God; the God to be worshipped and honored by thee; I only am thy God, and no other god is to be recognized or acknowledged by thee.” The foundation of the claim to exclusive service and devotion is here laid in the fact that he had brought them out of the land of Egypt. Literally, had caused them to ascend, or go up from that land. The claim thus asserted seems to be twofold:
(a) that in doing this, he had shown that he was God, or that he had performed a work which none but God could perform, and had thus shown his existence and power; and
(b) that by this he had brought them under special obligations to himself, inasmuch as they owed all that they had - their national existence and liberty - entirely to him.
Open thy mouth wide, and I will fill it - Possibly an allusion to young birds, when fed by the parent-bird. The meaning here is, “I can amply supply all your needs. You need not go to other gods - the gods of other lands - as if there were any deficiency in my power or resources; as if I were not able to meet your necessities. All your needs I can meet. Ask what you need - what you will; come to me and make any request with reference to yourselves as individuals or as a nation - to this life or the life to come - and you will find in me all abundant supply for all your needs, and a willingness to bless you commensurate with my resources.” What is here said of the Hebrews may be said of the people of God at all times. There is not a want of our nature - of our bodies or our souls; a want pertaining to this life or the life to come - to ourselves, to our families, to our friends, to the church, or to our country - which God is not able to meet; and there is not a real necessity in any of these respects which he is not willing to meet. Why, then, should his people ever turn for happiness to the “weak and beggarly elements of the world” (compare the notes at Galatians 4:9), as if God could not satisfy them? Why should they seek for happiness in vain amusements, or in sensual pleasures, as if God could not, or would not, supply the real needs of their souls?