Psalms 99:6

“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…”

“Moses - Moses before the institution of the priesthood executed that office, Exo 24:6. That call - Who used frequently and solemnly to intercede with God on the behalf of the people. Psalms 99:7”

“99:6-8 God showed favor by responding to his people in the past, while holding sinners accountable. 99:6 Moses and Samuel were great models and leaders who had prayed on behalf of the Lord’s people (Exod 32:31-32; 1 Sam 12:23).”

“Moses: Exo 24:6-8, 29:11-37, Exo 40:23-29; Num 16:47, Num 16:48 they called: Exo 14:15, Exo 15:25, Exo 32:11-14, Exo 33:12-15; Num 14:13-20, Num 16:21, Num 16:22; Sa1 7:9-12, Sa1 12:18-24; Jer 15:1 Psalms 99:7”

“The vision of the third Sanctus looks into the history of the olden time prior to the kings. In support of the statement that Jahve is a living God, and a God who proves Himself in mercy and in judgment, the poet appeals to three heroes of the olden time, and the events recorded of them. The expression certainly sounds as though it had reference to something belonging to the present time; and Hitzig therefore believes that it must be explained of the three as heavenly intercessors, after the manner of Onias and Jeremiah in the vision 2 Macc. 15:12-14. But apart from this presupposing an active manifestation of life on the part of those who have fallen happily asleep, which is at variance…”