John Calvin Commentary Isaiah 65:23

"They shall not labor in vain, nor bring forth for calamity; for they are the seed of the blessed of Jehovah, and their offspring with them." — Isaiah 65:23 (ASV)

They shall not toil in vain. He enumerates other kinds of blessings which God promises to the kingdom of Christ. For, although God always blessed his people, yet the blessings were in some measure suspended until the coming of Christ, in whom was displayed full and complete happiness. In a word, both Jews and Gentiles will be happy, in all respects, under the reign of Christ.

Now, as it is a sign of God’s wrath and curse when we obtain no advantage from our labor, so, on the other hand, it is a sign of blessing when we clearly see the fruit of our labor. For this reason he says that those who will have returned from captivity, in order that they may obtain a true and complete deliverance, will not spend their labor in vain or lose their efforts. The Law threatens the death of relatives, destructive wars, losses of property, and terror in their hearts (Leviticus 26:22; Deuteronomy 28:48). Here, on the contrary, are promised fertility, peace, the fruit of labor, and rest.

And blessings of this kind ought to be carefully observed, for there are few who, amid their labors, think of the blessing of God so as to ascribe everything to him alone and be fully convinced that they will accomplish nothing whatever unless the Lord grants them a prosperous result. Therefore, as every blessing should be sought from God, so, when it has been received, thanksgiving should be given for it to God alone.

And they shall not bring forth in terror. When it is said that women shall not bring forth in terror, some explain it to mean that they will have no uneasiness or dread of childbirth, because they will be free from pain. We know that this punishment was inflicted on the woman on account of sin, to bring forth with difficulty and to be in danger of death.

Children are brought into the world with fear and trembling when there is any expectation of war. It is probable that the Prophet rather considers this: that there will be such settled peace that neither women nor men will have any reason to fear. For this must be viewed as relating to both parents, who will have no dread about their children, as commonly happens when any danger is threatened.

For they shall be the seed of the blessed of Jehovah. This reason is highly appropriate; for from where do fears and terrors come, and from where do alarms come, if not from the curse of God? When the curse has been removed, the Prophet therefore rightly says that parents, together with their offspring, will be free from dread and anxious concern, because they will be convinced that they will always be safe and sound through the favor of God.

And their offspring with them. This is contrasted with childlessness, which is counted among the curses of God. Therefore, it is as if he had said, “I will no longer deprive them of their children, but will cause them to enjoy them, along with the rest of the blessings which I will bestow upon them.”