Stablish thy word unto thy servant - Confirm it; make it seem firm and true; let not my mind be vacillating or skeptical in regard to thy truth. This seems to be a prayer against the influence of doubt and scepticism; a prayer that doubts might not be suffered to spring up in his mind, and that the objections and difficulties of scepticism might have no place there. There is a class of people whose minds are naturally skeptical and unbelieving, and for such people such a prayer is especially appropriate. For none can it be improper to pray that the word of God may always seem to them to be true; that their minds may never be left to the influence of doubt and unbelief.
Who is devoted to thy fear - literally, “Who,” or which, “to thy fear.” This may refer either to the author of the psalm, or to the word of God. It may mean that he was among those who feared - that is, worshipped God; or, that the word of God had reference to the “fear,” that is, to the worship of God, or was designed to secure that. The construction seems to demand the latter interpretation; and then the prayer is, that God would confirm his faith in that “word” - in that revealed truth - which was designed to secure the worship of God.