Psalms 81:10

I am the Lord thy God,.... The true Jehovah, the Being of beings, in whom all live and move and have their beings, the covenant God of his people; and is a reason why they should hear him, and worship him, and no other:

which brought thee out of the land of Egypt; this, with what goes before, is the preface to the ten commands, the first and principal of which is urged in the preceding verse; and this is another reason why the Lord God should be had and worshipped, and not a strange god; and redemption from worse than Egyptian bondage, from the bondage of sin, Satan, and the law, and a deliverance from worse than Egyptian darkness, and from a state of wickedness and impiety, should lay under greater obligations still to serve the Lord, and worship him only; who adds, as a further reason for it,

open thy mouth wide, and I will fill it; which may be understood of opening the mouth either in prayer or in praise: to open the mouth wide in prayer is to pray with great freedom, to pour out the soul to God, lay open its whole case, and tell him all his mind and wants; to pray with great boldness, and with much importunity and fervency, and in full assurance of faith, pleading with great strength the promises of God, and asking in faith for much, according to them; and God may be said to fill this wide mouth of faith in prayer, when he grants the desires of the heart, gives his people what they will, even very largely and abundantly, yea, more than they can ask or think: to open the mouth wide in praise is to be abundantly thankful for mercies received; and when persons are so, the Lord fills them with more abundant matter for praise and thanksgiving; see Psalms 71:8, or this may be interpreted of opening the mouth wide in expressions of desire after spiritual food, hungering and thirsting after spiritual things, when the Lord fills or satisfies the mouths of his people with good things,

Psalms 103:5, with the sincere milk of the word which they desire, and with the ordinances, the breasts of consolation they long for, and so satisfies them with the goodness and fatness of his house, Psalms 64:4, the metaphor seems to be taken from the young of birds, which open their mouths, and are filled by the old ones: the Targum is,

"open thy mouth to the words of the law, and I will fill it with every good thing.''