Matthew Henry Bible Commentary

Observe here, 1. The good knowledge David had of the word of God; he knew it so well that he was ready to own, with the utmost satisfaction, that all God's commandments are not only righteous, but righteousness itself, the rule and standard of righteousness. 2. The good use he resolved to make of that knowledge: My tongue shall speak of thy word, not only utter praise for it to the glory of God, but discourse of it for the instruction and edification of others, as that which he himself was full of (for out of the abundance of the heart the mouth will speak) and as that which he desired others also might be filled with. The more we see of the righteousness of God's commandments the more industrious we should be to bring others acquainted with them, that they may be ruled by them. We should always make the word of God the governor of our discourse, so as never to transgress it by sinful speaking or sinful silence; and we should often make it the subject-matter of our discourse, that it may feed many and minister grace to the hearers.