John Calvin Commentary Exodus 18:19

"Hearken now unto my voice, I will give thee counsel, and God be with thee: be thou for the people to God-ward, and bring thou the causes unto God:" — Exodus 18:19 (ASV)

I will give you counsel. Jethro dares, indeed, to promise success if Moses will obey his counsel; yet he does not proudly boast that this will be the fruit of his own prudence, but ascribes it to God’s blessing and grace, if he prospers even when nothing is established except on the best system. For this is the meaning of the expression: that a plan occurs to him, which if Moses follows, God will bless him. Nor does he reprove Moses, as if God had not been up to this point with his pious zeal and industry, but rather hints that God is the author of this counsel, which He will follow up with His grace. In sum, he does not state it to be his object to diminish in the smallest degree the grace which Moses had already experienced, but to point out a plan of which God will, by its result, show His approval.

Then follows the other point to which I have alluded, namely, that he does not rob Moses of his authority, so as to overturn his call from God, but rather by exhorting him to proceed, desires that what God has once ordained should be firm and inviolable. We should also diligently consider that counsel should be taken according to circumstances and expediency, so that there should be no departure from the ordinance of God, because it is sinful to entertain the question of whether we should obey God or not. Accursed, then, are the deliberations in which it is proposed to alter anything in God’s Word, or to withdraw ourselves from the bounds of our calling.

We have said that the burden by which Moses was weighed down was not imposed by God; rather, he had only been set over the people as their leader, as far as his ability permitted. Jethro leaves this unaffected, and thus confirms by subscribing, as it were, to the decree of heaven. Because he was chosen to be an interpreter, and God intimately admitted him as the mediator between Him and His people, Jethro urges him to continue in the discharge of these duties. But because the possession of the supreme government did not interfere with the duty of a Prophet, he also desired that the greater matters be referred to him. For I interpret the expressions to mean that Moses was to be to God-ward, for the delivery of the rule of piety and for the performance of the prophetic office, while the weightier causes were to be referred by the rulers to him, so that everyone might receive justice.