Psalms 104:28

That thou givest them they gather - What thou dost place before them they collect. They have no resources of their own. They can invent nothing; they cannot vary their food by art, as man does; they cannot make use of reason, as man does, or of skill, in preparing it, to suit and pamper the appetite. It comes prepared for them direct from the hand of God.

Thou openest thine hand - As one does who bestows a gift on another. The point in the passage is, that they receive it immediately from God, and that they are wholly dependent on him for it. They have not to labor to prepare it, but it is made ready for them, and they have only to gather it up. The allusion in the “language” may be to the gathering of manna in the wilderness, when it was provided by God, and people had only to collect it for their use. So it is with the brute creation on land and in the waters.

They are filled with good - They are “satiated” with good; that is, They are satisfied with what to them is good, or with what supplies their needs.