Psalms 54:6

I will freely sacrifice unto thee - Or, I will sacrifice nobly unto thee. Not only with a willing mind, but with a liberal hand will I bring sacrifice unto thee.

For it is good - Thy name is good; it is descriptive of thy nature; full of goodness and mercy to man. And it is good to be employed in such a work: whoever worships thee in sincerity is sure to be a gainer. To him who orders his conversation aright, thou dost show thy salvation.

I will freely sacrifice unto thee - The Hebrew words rendered "freely," mean with "willingness, voluntariness, spontaneousness." The idea is, that he would do it of a free or willing mind; without constraint or compulsion; voluntarily. The reference is to a free-will or voluntary offering, as distinguished from one, that was prescribed by law. See Exodus 35:29; Exodus 36:3; Leviticus 7:16; Leviticus 22:18; Numbers 15:3; Numbers 29:39. The idea is, that as the result of the divine interposition which he prayed for, he would bring voluntary offerings to God in acknowledgment of his goodness and mercy.

I will praise thy name, O Lord - I will praise thee. See Psalm 52:9.

For it is good - That is, God himself is benevolent; and David says that he would express his sense of God's goodness by offering him praise.