John Calvin Commentary Genesis 12:17

"And Jehovah plagued Pharaoh and his house with great plagues because of Sarai, Abram`s wife." — Genesis 12:17 (ASV)

And the Lord plagued Pharaoh. If Moses had simply related that God had punished the king for having committed adultery, it would not so obviously appear that He had taken care of Sarai’s chastity. But when he plainly declares that the house of the king was plagued because of Sarai, Abram’s wife, all doubt is, in my judgment, removed. This is because God, on behalf of His servant, interposed His mighty hand in time, so that Sarai would not be violated. And here we have a remarkable instance of the attentive care with which God protects His servants by undertaking their cause against the most powerful monarchs, as this and similar histories show, which are referred to in Psalm 105:12-15:

When they were but a few men in number; yea, very few, and strangers in it. When they went from one nation to another, from one kingdom to another people; he suffered no man to do them wrong; yea, he reproved kings for their sakes; saying, Touch not mine anointed, and do my prophets no harm.

From this passage, a confirmation of the opinion just given may also be derived. For if God reproved Pharaoh so that he would do Abram no harm, it follows that He preserved Sarai’s honor uninjured. Instructed by such examples, we may also learn that however the world may hold us in contempt on account of the smallness of our number and our weakness, we are yet so precious in the sight of God that He will, for our sake, declare Himself an enemy to kings, and even to the whole world.

Let us know that we are covered by His protection, so that the lust and violence of those who are more powerful may not oppress us. But it is asked whether Pharaoh was justly punished, since he neither intended, by guile nor by force, to gain possession of another man’s wife.

I answer that the actions of men are not always to be estimated according to our judgment but are rather to be weighed in the balances of God, for it often happens that the Lord will find in us what He may justly punish, while we seem to ourselves to be free from fault and while we absolve ourselves from all guilt.

Let kings rather learn from this history to bridle their own power, to use their authority moderately, and finally, to impose a voluntary law of moderation upon themselves. For although no fault openly appears in Pharaoh, yet since he has no faithful monitor among men who dares to repress his licentiousness, the Lord chastises him from heaven.

As to his family, it was indeed innocent; but the Lord always has just causes, though hidden from us, why He should strike with His rod those who seem to merit no such rebuke. That He spared His servant Abram ought to be ascribed to His paternal indulgence.