Matthew Poole and continuators on Deuteronomy 32:4

4 He is the rock , his work is perfect : for all his wayes are judgment : a God of truth , and without iniquity, just and right is he.

Or, a rock, as for the stability and everlastingness of his nature, and invincibleness of his power, so also for his fixedness and immutability in his counsels and promises and wayes; so that if there shall be a sad change in your affairs from an high and prosperous, to a calamitous and deplorable, condition, as there will be, remember this proceeds from your selves and from the change of your ways and carriages towards God, and not from God, in whom there is no variableness nor shadow of change, Iam. 1. 17.

All his works and actions are unblameable, as being perfectly wise and righteous, as it follows.

All his administrations in the world and particularly all his dealings with you are managed with judgment and justice.

Constant to his promises: you cannot accuse him of any levity or unfaithfulness towards you to this day.