In Salem also - This was the ancient name for Jerusalem, and is evidently so used here. It continued to be given to the town until the time of David, when it was called “Jerusalem.” See the notes at Isaiah 1:1. The word properly means “peace,” and is so rendered here by the Septuagint, ἐν εἰρήνῃ ὁ τόπος αύτοῦ en eirēnē ho topos autou - “his place is in peace.” There may have been an allusion here to that ancient signification of the name, as being more poetical, and as suggesting the fact that God had restored peace to the city and nation when invaded.
Is his tabernacle - The tent, or sacred place where he is worshipped. Salem or Jerusalem was made the place of public worship, and the ark removed there by David, 2 Samuel 6:17.
And his dwelling-place in Zion - That is, on Mount Zion - the portion of Jerusalem in which David built his own palace, and which he made the place of public worship. This remained so until the temple was built on Mount Moriah; see the notes at Psalms 2:6; compare Psalms 9:11; Psalms 48:12; Psalms 65:1.