And he appointed certain of the Levites to minister before the ark of the LORD, and to record, and to thank and praise the LORD God of Israel:
To thank, and praise — All our rejoicings should express themselves in thanksgivings to him, from whom all our comforts are received.
 Then on that day David delivered first this psalm to thank the LORD into the hand of Asaph and his brethren.
First — Hereby it is implied, that after this he delivered many other psalms into their hands, to be sung by them to the praise of God in his public service. We shall find it in the same words, in Psalms 105:1-15 and Psalms 96:1-11, all but the three last verses.
 And say ye, Save us, O God of our salvation, and gather us together, and deliver us from the heathen, that we may give thanks to thy holy name, and glory in thy praise.
From the Heathen — This psalm or prayer was made by David for the use of the church, not only in that present time, but in future ages, in which David foresaw by the spirit of prophecy, the Israelites would forsake God, and for their apostacy be dispersed among the Heathens. In the midst of our praises, we must not forget to pray for those servants of God that are in distress. When we are rejoicing in God's favours, we should remember our afflicted brethren, and pray for their deliverance as our own. We are members one of another.
 So he left there before the ark of the covenant of the LORD Asaph and his brethren, to minister before the ark continually, as every day's work required:
He left — He appointed them their work and station there. Indeed no incense was burnt there, nor sacrifices offered, because the altars were not there. But David's prayers were directed as incense, and the lifting up of his hands as an evening sacrifice. So early did spiritual worship take place of ceremonial.
 And Zadok the priest, and his brethren the priests, before the tabernacle of the LORD in the high place that was at Gibeon,
Zadok — The chief-priest at Gibeon, where the tabernacle and altar made by Moses still were, where also the ordinary sacrifices were offered, and the stated worship of God was performed, as the extraordinary worship was before the ark upon great occasions, as when God was consulted, which was to be done before the ark and by the high-priest, who was Abiathar.
 To offer burnt offerings unto the LORD upon the altar of the burnt offering continually morning and evening, and to do according to all that is written in the law of the LORD, which he commanded Israel;
Which he commanded Israel — These must be kept up; because however in their own nature they were inferior to prayer and praise, yet as they were types of the mediation of Christ, the observance of them was of mighty importance.
 And with them Heman and Jeduthun with trumpets and cymbals for those that should make a sound, and with musical instruments of God. And the sons of Jeduthun were porters.
Of God — Appropriated to the worship of God; not such as they used on other occasions. Between common mirth and holy joy, there is a vast difference: and the limits and distances between them must be carefully kept up.