Psalms 99:6

Moses and Aaron among his priests, and Samuel among them that call upon his name. Though not ordained to the typical priesthood, Moses was a true priest, even as Melchizedek had been before him. God has ever had a priesthood beside and above that of the law. The three holy men here mentioned all stood in his courts, and saw his holiness, each one after his own order. Moses saw the Lord in flaming fire revealing each perfect law, Aaron full often watched the sacred fire devour the sin-offering, and Samuel witnessed the judgment of the Lord on Eli's house, because of the error of his way. These each one stood in the gap when the wrath of God broke forth, because his holiness had been insulted; and acting as intercessors, they screened the nation from the great and terrible God, who otherwise would in a dreadful manner have executed judgment in Jacob. Let these men, or such as these, lead us in our worship, and let us approach the Lord at the mercy-seat as they did, for he is as accessible to us as to them. They made it their life's business to call upon him in prayer, and by so doing brought down innumerable blessings upon themselves and others. Does not the Lord call us also to come up into the mount with Moses, and to enter the most holy place with Aaron? Do we not hear him call us by our name as he did Samuel? And do we not answer, "Speak, Lord, for thy servant heareth"? They called upon the Lord, and he answered them. Not in vain were their prayers; but being a holy God he was true to his promises, and hearkened to them from off the mercy-seat. Here is reason for praise, for answers to the petitions of some are proofs of God's readiness to hear others. These three men asked large things, they pleaded for a whole nation, and they stayed great plagues and turned away fiery wrath; who would not exercise himself in adoring so great and merciful a God?

Moses and Aaron - As Moses and Aaron among the priests, and as Samuel among the prophets, worshipped God in humility, gratitude, and the spirit of obedience, and received the strongest tokens of the Divine favor; so worship ye the Lord, that he may bless, support, and save you. Moses was properly the priest of the Hebrews before Aaron and his family were appointed to that office.

Moses and Aaron among his priests - Among the ministers of religion; or, as officiating in the service of God. Let them come as representatives of their order - as representing those who conduct the public worship of God, and join in his praise. The idea is, that all mankind should join in his praise, and those mentioned here as among the most eminent of those who were engaged in directing the public worship of God. Moses could be called a “priest” only in the most general sense of the term, as having been employed in directing and arranging for public worship, and as being of the original tribe of Levi, from whom the whole sacerdotal order sprang. And Samuel among them that call upon his name - Among those who are true worshippers, in distinction from the priests who were specially appointed to the public service of God. The idea is, that praise should be offered by “all” classes: by priests and by people. As Moses and Aaron were among the most eminent of the former class, so Samuel was among the most distinguished of those who were not of the priestly order. These were “representative men;” and the meaning is, that all who were of their order or rank - priests and people - should unite in the worship of God. They called upon the Lord - They did call upon the Lord; they worshipped Yahweh. They gave the influence of their names and of their position to his public service. They thus showed their sense of the propriety of praising God; they gave the countenance of their example to public worship and praise; and the benefits which they received in answer to prayer showed the propriety and advantage of thus publicly acknowledging God. And he answered them - They did not call upon him in vain. He heard their prayers. He bestowed blessings on them in connection with their worship. It was not a useless thing to praise and worship him. […]