Objection 1. It seems that God need not be obeyed in all things. For it is written (Matthew 9:30-31) that our Lord after healing the two blind men commanded them, saying: "See that no man know this. But they going out spread His fame abroad in all that country." Yet they are not blamed for so doing. Therefore it seems that we are not bound to obey God in all things.
Objection 2. Further, no one is bound to do anything contrary to virtue. Now we find that God commanded certain things contrary to virtue: thus He commanded Abraham to slay his innocent son (Genesis 22); and the Jews to steal the property of the Egyptians (Exodus 11), which things are contrary to justice; and Osee to take to himself a woman who was an adulteress (Hosea 3), and this is contrary to chastity. Therefore God is not to be obeyed in all things.
Objection 3. Further, whoever obeys God conforms his will to the divine will even as to the thing willed. But we are not bound in all things to conform our will to the divine will as to the thing willed, as stated above (I-II, 19, 10). Therefore man is not bound to obey God in all things.
On the contrary, It is written (Exodus 24:7): "All things that the Lord hath spoken we will do, and we will be obedient."
I answer that, As stated above (Article 1), he who obeys is moved by the command of the person he obeys, just as natural things are moved by their motive causes. Now just a God is the first mover of all things that are moved naturally, so too is He the first mover of all wills, as shown above (I-II, 09, 6). Therefore just as all natural things are subject to the divine motion by a natural necessity so too all wills, by a kind of necessity of justice, are bound to obey the divine command.
Reply to Objection 1. Our Lord in telling the blind men to conceal the miracle had no intention of binding them with the force of a divine precept, but, as Gregory says (Moral. xix), "gave an example to His servants who follow Him that they might wish to hide their virtue and yet that it should be proclaimed against their will, in order that others might profit by their example."
Reply to Objection 2. Even as God does nothing contrary to nature (since "the nature of a thing is what God does therein," according to a gloss on Romans 11), and yet does certain things contrary to the wonted course of nature; so to God can command nothing contrary to virtue since virtue and rectitude of human will consist chiefly in conformity with God's will and obedience to His command, although it be contrary to the wonted mode of virtue. Accordingly, then, the command given to Abraham to slay his innocent son was not contrary to justice, since God is the author of life an death. Nor again was it contrary to justice that He commanded the Jews to take things belonging to the Egyptians, because all things are His, and He gives them to whom He will. Nor was it contrary to chastity that Osee was commanded to take an adulteress, because God Himself is the ordainer of human generation, and the right manner of intercourse with woman is that which He appoints. Hence it is evident that the persons aforesaid did not sin, either by obeying God or by willing to obey Him.
Reply to Objection 3. Though man is not always bound to will what God wills, yet he is always bound to will what God wills him to will. This comes to man's knowledge chiefly through God's command, wherefore man is bound to obey God's commands in all things.
Source: Summa Theologica (New Advent)