Albert Barnes Commentary Psalms 134:3

"Jehovah bless thee out of Zion; Even he that made heaven and earth." — Psalms 134:3 (ASV)

The Lord that made heaven and earth—The great Creator of all things. This is probably the language of those who were in this way employed in the service of the Lord at night; their response to the address in the first two verses.

Bless thee out of Zion—That is, bless those who in this way approached the sanctuary, and called on those within to praise the Lord. This is the answer. Let the blessing of God rest on you. It is language showing that they appreciated the kind and encouraging salutation, and that they reciprocated the feelings and the good wishes of those who came to worship.

In the name of the Lord whom they served, therefore, and appealing to him, they pronounced a blessing on those who in this way approached the sanctuary. People do not come near the house of God—the place of public worship—with kind and sympathizing feelings without a blessing from the sanctuary, without a response that welcomes them and meets all their aspirations. There is always in Zion—in the church—a voice, by day and night, which pronounces a blessing on those who wish it well, who seek its good, and who desire to partake of the favor of God.

Out of Zion—That is, may God speak to you out of Zion; may he confer on you such blessings as properly go out of Zion, or such as Zion (or his church) can furnish. Do not go away unblessed; do not go without a token of divine favor—for God will bless you.