John Calvin Commentary Genesis 42:17

"And he put them all together into ward three days." — Genesis 42:17 (ASV)

And he put them altogether into ward. Here, not by words only, as before, but by the act itself, Joseph shows himself severe towards his brothers. He shuts them all up in prison, as if about to bring them to punishment, and for three days he torments them with fear.

We said a little while ago that from this act no rule for acting severely and rigidly should be drawn, because it is doubtful whether he acted rightly or otherwise. Again, it is to be feared that those who plead his example might be far removed from his mildness and prove to be his apes rather than his true imitators.

Meanwhile, it plainly appears what he was aiming at, for he does not mitigate their punishment, as if he were appeased at the end of three days; instead, he makes them more anxious about the redemption of their brother, whom he retains as a hostage. However, to prevent immoderate fear from deterring them from returning, he promises to act in good faith towards them. To convince them of this, he declares that he fears God—an expression worthy of observation.

Doubtless he speaks from the inward feeling of his heart when he declares that he will deal well and truly with them because he fears God. Therefore, the beginning and the source of that good and honest conscience, by which we cultivate faithfulness and justice towards others, is the fear of God.

Indeed, some uprightness may appear in those who despise God, but it soon goes off in smoke unless the corrupt desires of the flesh are restrained, as if with a bridle, by the thought that God is to be feared because He will be the Judge of the world. For whoever does not think that he must give an account will never cultivate such integrity as to refrain from pursuing what he supposes will benefit himself.

Therefore, if we wish to be free from perfidy, craft, cruelty, and all wicked desire to do injury, we must work earnestly for religion to flourish among us. For whenever we act with a lack of sincerity or humanity towards each other, impiety openly reveals itself. For whatever uprightness or justice there is in the world, Joseph encapsulated it in this short sentence when he said that he feared God.