Stablish thy word unto thy servant
Either God's word of promise, which never fails, is firm and stable in Christ; and the sense is, that God would assure him of the fulfilment of it, and give him a strong faith and firm belief of it; for otherwise the word of the Lord cannot be surer or more stable than it is: or else the word of his grace; and then the sense is, that he might be established in it, and the truths of it, and be established by it; for the word is a means of establishment, and a good thing it is to have the heart established with grace, with the doctrine of grace, ( Hebrews 13:9 ) ;
who [is devoted] to thy fear;
who served the Lord with reverence and godly fear; who feared the Lord and his goodness; that grace being a reigning one in his heart, and ever before his eyes. Or, "which is unto thy fear" F4; that is, which word is unto thy fear; which leads unto it, and has a tendency to promote and increase it; and so is a commendation of the word of God from this effect of it.
F4 (Ktaryl rva) "quod ad timorem tuum", Pagninus, Montanus; "quod ad timorem tui facit", Musculus; "et ducit", Schmidt; "quod datum est ad timorem tui", Michaelis.