Charles Spurgeon Commentary Deuteronomy 32:4

"The Rock, his work is perfect; For all his ways are justice: A God of faithfulness and without iniquity, Just and right is he." — Deuteronomy 32:4 (ASV)

He is the rock,
Immutable, eternal.

His work is perfect:

Sometimes very terrible and very mysterious, but His work is perfect.

For all his ways are judgment: a God of truth and without iniquity, just and right is he.

But as for his people, what a contrast between them and their God!