The worship of God is not only to be the work of a solemn day now and then, brought in to grace a triumph; but it ought to be the work of every day. David therefore settles it here for a constancy, puts it into a method, which he obliged those that officiated to observe in their respective posts. In the tabernacle of Moses, and afterwards in the temple of Solomon, the ark and the altar were together; but, ever since Eli's time, they had been separated, and still continued so till the temple was built. I cannot conceive what reason there was why David, who knew the law and was zealous for it, did not either bring the ark to Gibeon, where the tabernacle and the altar were, or bring them to Mount Zion, where the ark was. Perhaps the curtains and hangings of Moses's tabernacle were so worn with time and weather that they were not fit to be removed, nor fit to be a shelter for the ark; and yet he would not make all new, but only a tent for the ark, because the time was at hand when the temple should be built. Whatever was the reason, all David's time they were asunder, but he took care that neither of them should be neglected. 1. At Jerusalem, where the ark was, Asaph and his brethren were appointed to attend, to minister before the ark continually, with songs of praise, as every day's work required, Ch1 16:37. No sacrifices were offered there, nor incense burnt, because the altars were not there: but David's prayers were directed as incense, and the lifting up of his hands as the evening sacrifice (Psa 141:2), so early did spiritual worship take place of ceremonial. 2. Yet the ceremonial worship, being of divine institution, must by no means be omitted; and therefore at Gibeon were the altars where the priests attended, for their work was to sacrifice and burn incense, which they did continually, morning and evening, according to the law of Moses, Ch1 16:39, Ch1 16:40. These must be kept up because, however in their own nature they were inferior to the moral services of prayer and praise, yet, as they were types of the mediation of Christ, they had a great deal of honour put upon them, and the observance of them was of great consequence. Here Zadok attended, to preside in the service of the altar; as (it is probable) Abiathar settled at Jerusalem, to attend the ark, because he had the breast-plate of judgment, which must be consulted before the ark: this is the reason why we read in David's time both Zadok and Abiathar were the priests (Sa2 8:17; Sa2 20:25), one where the altar was and the other where the ark was. At Gibeon, where the altars were, David also appointed singers to give thanks to the Lord, and the burden of all their songs must be, For his mercy endureth for ever, Ch1 16:41. They did it with musical instruments of God, such instruments as were appointed and appropriated to this service, 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 observed and kept up. Matters being thus settled, and the affairs of religion put into a happy channel, (1.) The people were satisfied, and went home pleased. (2.) David returned to bless his house, resolving to keep up family worship still, which public worship must not supersede.

Save us, O God of our salvation - As he is the saving God, so we may pray to him to save us. To pray to God under the attribute the influence of which we need, serves to inspire much confidence. I am weak; Almighty God, help me! I am ignorant; O thou Father of lights, teach me! I am lost; O merciful God, save me; etc. See the notes on Psa 96:1-13 (note) and Psalm 105 (note).

To offer burnt offerings unto the Lord,.... Which was the work of the priests only to do:

upon the altar of burnt offering continually morning and evening; the lambs of the daily sacrifice, which were a burnt offering, and only to be offered on the brasen altar at the tabernacle:

and to do according to all that is written in the law of the Lord, which he commanded Israel; with regard to them, and all other sacrifices, see Exo 29:38.

Obed-edom with their brethren--Hosah, mentioned at the close of the verse, and a great number besides (see on Ch1 26:1).

to be porters--doorkeepers.