Here is, 1. David's great affection for the word of God: Thy servant loves it. Every good man, being a servant of God, loves the word of God, because it lets him know his Master's will and directs him in his Master's work. Wherever there is grace there is a warm attachment to the word of God. 2. The ground and reason of that affection; he saw it to be very pure, and therefore he loved it. Our love to the word of God is then an evidence of our love to God when we love it for the sake of its purity, because it bears the image of God's holiness and is designed to make us partakers of his holiness. It commands purity, and, as it is itself refined from all corrupt mixture, so if we receive it in the light and love of it it will refine us from the dross of worldliness and fleshly-mindedness.

The righteousness of thy testimonies is everlasting,.... Or, "for ever" (b). The righteousness which they require, or which they publish; the righteousness revealed in the Gospel, which is the righteousness of Christ; See Gill on Psa 119:142;

give me understanding, and I shall live; an understanding of the testimonies of the Lord, of the word of God, the law of God, and Gospel of Christ; an understanding of divine and spiritual things; a clearer and larger understanding of them, which is the gift of God; both that itself at first, and an increase of it here prayed for, the end, issue, and effect of which is life. Such live spiritually, and by faith; they live cheerfully and comfortably, and "for ever", as Aben Ezra and Kimchi repeat from the former clause: for "this is life eternal know the only true God and Jesus Christ"; or to have spiritual understanding of them, and of those things which relate to spiritual peace and comfort here, and eternal happiness hereafter, Joh 17:3.

(b) "in seculum", Pagninus, Montanus, Junius & Tremellius, Piscator, Cocceius; "in aeternum", V. L.