John Calvin Commentary Psalms 33:4

"For the word of Jehovah is right; And all his work is [done] in faithfulness." — Psalms 33:4 (ASV)

For the word of Jehovah is right. As I have just remarked, the Psalmist first sets forth God’s general providence by which he governs the whole world; and he tells us that he so exerts his power in the whole course of his operations, that the most perfect equity and faithfulness shine forth everywhere.

Some would have the terms word and work to be synonymous; but I think there is a distinction, and that word means the same thing as counsel or ordinance, while work signifies the effect or execution of his counsel. I grant that here the same subject is repeated in different words, as is the case in other places; but a slight variation will be found in such repetitions, so that the same thing may be expressed in various ways.

The substance of what is stated is, that whatever God appoints and commands is right; and whatever he brings to pass in actual operation is faithful and true. Meanwhile, it should be observed, that the term word is not to be understood as doctrine, but as the method by which God governs the world.