The design of these verses is,

I.To arm the people of God against idolatry and all false worship, by showing what sort of gods they were that the heathen worshipped, as we had it before, Psa 115:4, etc. 1. They were gods of their own making; being so, they could have no power but what their makers gave them, and then what power could their makers receive from them? The images were the work of men's hands, and the deities that were supposed to inform them were as much the creatures of men's fancy and imagination. 2. They had the shape of animals, but could not perform the least act, no, not of the animal life. They could neither see, nor hear, nor speak, nor so much as breathe; and therefore to make them with eyes, and ears, and mouths, and nostrils, was such a jest that one would wonder how reasonable creatures could suffer themselves to be so imposed upon as to expect any good from such mock-deities. 3. Their worshippers were therefore as stupid and senseless as they were, both those that made them to be worshipped and those that trusted in them when they were made, Psa 135:18. The worshipping of such gods as were the objects of sense, and senseless, made the worshippers sensual and senseless. Let our worshipping a God that is a Spirit make us spiritual and wise.

II.To stir up the people of God to true devotion in the worship of the true God, Psa 135:19-21. The more deplorable the condition of the Gentile nations that worship idols is the more are we bound to thank God that we know better. Therefore, 1. Let us set ourselves about the acts of devotion, and employ ourselves in them: Bless the Lord, and again and again, bless the Lord. In the parallel place (Psa 115:9-11), by way of inference from the impotency of idols, the duty thus pressed upon us is to trust in the Lord; here to bless him; by putting our trust in God we give glory to him, and those that depend upon God shall not want matter of thanksgiving to him. All persons that knew God are here called to praise him - the house of Israel (the nation in general), the house of Aaron and the house of Levi (the Lord's ministers that attended in his sanctuary), and all others that feared the Lord, though they were not of the house of Israel. 2. Let God have the glory of all: Blessed be the Lord. The tribute of praise arises out of Zion. All God's works do praise him, but his saints bless him; and they need not go far to pay their tribute, for he dwells in Jerusalem, in his church, which they are members of, so that he is always nigh unto them to receive their homage. The condescensions of his grace, in dwelling with men upon the earth, call for our grateful and thankful returns, and our repeated Hallelujahs.

Bless the Lord, O house of Levi,.... These were of the same tribe with the house of Aaron, but inferior ministers; they ministered to the priests, and had the charge of things in the tabernacle and temple; many of them were porters in the latter, and others were singers, and of these Kimchi interprets the words; whose work it was to give thanks morning and evening, and so are with great propriety called upon to bless the Lord, Num 3:6; and may mystically design inferior officers in the church, who are helps and assistants to ministers in the government and discipline of it, and have the care of its secular affairs; and who, when they behave well, purchase to themselves a good degree, and boldness in the faith; and even doorkeepers in the house of the Lord have reason to bless his name for a place there; and all the saints are the sweet singers of Israel, have the new song of electing, redeeming, and calling grace, put into their mouths, and therefore should bless the Lord;

ye that fear the Lord, bless the Lord; these are distinct from the Israelites, priests, and Levites, and design the proselytes among them of other nations that truly feared God, as Jarchi notes; and all such persons, whoever and wherever they are, have reason to bless the Lord for the fear of him they have, which is not from nature, but from grace; and for the layouts shown them, the blessings bestowed upon them, the good things laid up for them, and the guard that is about them, which the Scriptures abundantly declare, and experience confirms.