John Calvin Commentary Jeremiah 31:29-30

"In those days they shall say no more, The fathers have eaten sour grapes, and the children`s teeth are set on edge. But every one shall die for his own iniquity: every man that eateth the sour grapes, his teeth shall be set on edge." — Jeremiah 31:29-30 (ASV)

Ezekiel shows that it was a complaint prevalent among the people that they suffered for the sins of their fathers. As Horace, a pagan and a despiser of God, also says, “O Roman, you undeservedly suffer for the faults of your fathers.” Such, then, was the arrogance of the Jews that they contended with God, as if He punished them while they were innocent. They expressed this by using a proverb: If our fathers have eaten sour grapes, what is the reason that our teeth are set on edge?

We know that teeth are set on edge when unripe fruits are eaten; but the word properly means sour grapes, which the Greeks call omphakes. Then the Prophet says that this proverb would no longer be used, for after being subdued by afflictions, they would eventually know that God had not dealt so severely with them without a just cause.

We now understand the meaning of the Prophet. And he says, In those days, that is, after God had punished the people and also embraced them in His mercy; for both these things were necessary: their stubbornness and pride had to be subdued, and they had to stop arguing with God; additionally, the free favor of God had to be revealed to them.

At that time then, he says, they shall not use this ungodly proverb, The fathers have eaten a sour grape, and the children’s teeth have been blunted: but on the contrary, he adds, every one shall die in his own iniquity; and whoever eats a sour grape, his teeth shall be blunted. That is, at that time the just judgment of God will be exalted, so that there will be no place for these insolent and blasphemous outcries. The mercy of God will also be revealed, for people worthy of death will be delivered, but only through the free goodness of God.

Prayer:

Grant, Almighty God, that since you warn us daily by so many evidences of your wrath, we may repent in due time — O grant that we may not be slow to consider your work and also the doctrine which you add, but rather anticipate your extreme vengeance, and thus be made capable of receiving your mercy, so that as you freely offer it to us, we may eagerly embrace it, and also so retain it in our hearts by true faith, that you may continue its course toward us, until we finally reach that blessed rest, which has been prepared for us in heaven by Christ our Lord. Amen.