99:3 it is holy. The name of God is holy (Psalm 99:3), He is holy (Psalm 99:5), and on His holy hill, He is holy (Psalm 99:9). This thrice-holy God is, indeed, “high and lifted up” (Isaiah 6:1, 3). Note that the cherubim are present (Psalm 99:1), just as the seraphim (Isaiah 6:2).
Psalm 100 (title) A Psalm of praise. Although the book of Psalms has been called “the Book of the Praises of Israel, this is one of the only two psalms with this specific heading. The word used here for “praise” is more commonly translated “thanksgiving” and is so rendered in Psalm 100:4. The other “Psalm of praise” is Psalm 145.