Charles H. Spurgeon on Psalms 99:6

They that call upon his name. The Hebrew word which we translate to call upon God, notes a sort of men whose chief business or trade was to call upon or invocate the name of God, and in this instance it implies that it was the special calling of these men to call upon God. Joseph Caryl.

Verses 6-9. This third strophe is in reality a prophetical picture of the future holy worship of God, in which Moses, Aaron, and Samuel appear as the living representatives of the redeemed church, like the four and twenty elders in the more fully developed Apocalyptic scene of St. John. Revelation 5. Joseph Francis Thrupp.