A call to praise the thrice-holy sovereign God of Israel for his grace.
st. 1 = vv. 1-3
st. 2 = vv. 4-5
st. 3 = vv. 6-9
The Levites used Psalm 99 in the liturgy of a yearly high religious festival celebrating the LORD's worldwide rule (perhaps the Feast of Tabernacles). The psalm opens with a call to all nations to praise the God of Israel (st. 1), exhorts Israel to exalt their mighty King for performing righteous deeds in their behalf (st. 2), and recalls examples of God's gracious response to Israel's need for deliverance. It closes with a grateful remembrance of God's forgiveness (st. 3). Verses 3,5, and 9 close with "God is holy," a poetic echo of the trisagion (see Isa. 6:3) and a reflection of the ancient liturgical penchant for triple repetition. The versification (altered) is from the 1912 Psalter.
Ascension (see also 47, 93, and 110); like the others in the cluster 92-100, this psalm is appropriate for many different worship occasions.
--Psalter Hymnal Handbook, 1988