Sing forth. — Literally, play on the harp.
Make his praise glorious. — So the LXX., but the construction is dubious. Literally, put glory his praise, meaning perhaps, in parallelism with the first clause, “make the Divine glory the subject of your praise.” But the opening words of the next verse, “say unto God, how,” &c, are so bald that a suspicion arises as to the arrangement of the text. Perhaps by bringing back the initial words of Psalms 66:3 we get the true sense, “ascribe glory (and) speak praise to God.”