Exalt the Lord our God - See the notes at Psalm 99:5.
And worship at his holy hill - In Psalm 99:5, this is, "at his footstool." The "holy hill" refers to Zion, as the seat of the national worship.
For the Lord our God is holy - See Psalm 99:5. This appropriately closes the psalm, by a distinct and solemn statement that the fact that Yahweh is a holy God is a reason for worshipping him. This is at all times the highest reason for adoration and praise.

Worship at his holy hill - Worship him publicly in the temple.
For the Lord our God is holy - The words of the chorus; as in the third and fifth verses.

Exalt the Lord our God,.... Having given the above instances of Moses, Aaron, and Samuel, serving and worshipping the Lord, the psalmist repeats the exhortation in Psalm 99:5, which he enforces by their example; See Gill on Psalm 99:5,
and worship at his holy hill; the holy hill of Zion, the church; attend the public worship and service of it: the Targum is,
"worship at the mountain of the house of his sanctuary; the temple, a type of the church of Christ:''
for the Lord our God is holy; his nature is holy, and he is glorious in the perfection of his holiness, and therefore to be praised and exalted; and his name is holy, and so reverend, and therefore to be worshipped; see in Psalm 99:3.