John Calvin Commentary Isaiah 38:7

"And this shall be the sign unto thee from Jehovah, that Jehovah will do this thing that he hath spoken:" — Isaiah 38:7 (ASV)

And this shall be a sign to thee. The sacred history relates in the proper order that Hezekiah asked a sign from the Lord (2 Kings 20:8), and that it was granted to him, which the Prophet will also mention at the end of this chapter. But it is no new thing for Hebrew writers to reverse the order of the narrative.

God gives some signs of His own accord, without being asked, and He grants other signs to His people who ask them. Signs are generally intended to aid our weakness, so God does not for the most part wait until we have prayed for them; instead, He first appointed those which He knew to be profitable to His Church.

If at any time, therefore, believers wished to have their faith confirmed by a sign, this circumstance, being rare, ought not to be produced as an example. Thus, to Gideon, whom He called from the sheepfold to govern Israel, He gave one sign and then another when Gideon asked for them (Judges 6:17, 37, 39), so that he might be more fully convinced of his calling.

As we have said, God commonly gave other signs to accommodate the weakness of men: for example, to Adam the tree of life (Genesis 2:9), to Noah the bow in heaven (Genesis 9:12), next the cloud and pillar of fire (Exodus 13:21), and the serpent of brass in the wilderness (Numbers 21:8). The same remarks apply to the Passover (Exodus 12:8) and to all the sacraments, both those which were formerly observed and those which have now been appointed by Christ, and which no one asked from God.

But it may be thought that Hezekiah insults God by refusing to believe His word when he asks for a sign. I reply, we must not accuse him of unbelief because his faith was weak, for we will not find any person who ever had faith that was perfect and complete in every respect. In seeking some assistance to support his weakness, he cannot be blamed on that account; for, having embraced the promise made to him by the Prophet, he shows his confidence in God by seeking a remedy for distrust.

Indeed, if there had been no weakness in humanity, we would not have needed any signs. Consequently, we need not wonder that Hezekiah asks for a sign, since on other occasions the Lord freely offers them.

Yet it is also proper to observe that believers never rushed forward at random to ask for signs but were guided by a secret and special influence of the Spirit. The same thing might be said about miracles. If Elijah prayed to God for rain and for drought (James 5:17–18), it does not follow that others are at liberty to do the same. We must, therefore, discern what God permits us, lest, by disregarding His word, we bargain with Him according to the foolish desires of our flesh.