John Calvin Commentary Isaiah 48:19

"thy seed also had been as the sand, and the offspring of thy bowels like the grains thereof: his name would not be cut off nor destroyed from before me." — Isaiah 48:19 (ASV)

Thy seed would have been as the sand. This also relates to a happy life, when offspring is multiplied, by whose help the labors of the elderly are eased, and which resists the adversaries in the gate. The Psalmist compares such children to arrows shot by a strong hand, and pronounces him to be blessed who hath his quiver full of them; that is, who has a large number of such children (Psalms 127:4, 5).

When he mentions sand, he appears to allude to the promise which was made to Abraham,

I will multiply thy seed as the stars of heaven, and as the sand which is on the sea-shore (Genesis 22:17).

And he repeats the same sentiment in various words, according to the usage of the Hebrew writings, substituting children for “seed,” and small stones for “sand.” In a word, he shows that the people prevented God from causing them to enjoy the fruit of that promise.

His name would not have been cut off. Addressing the interruption of this favor, he next reproaches them in more direct terms with having sought dispersion after being miraculously collected by the hand of God. For by the word name he means the lawful condition of the people, which would always have flourished if the blessing had not been turned aside from its course.

What he says about the people having been “cut off” must be understood to refer to the land of Canaan, from which the people of God had been cast out and thus appeared to have been thrust out of their Father’s house. For the Temple, of which they were deprived, was a symbol of God’s presence, and the land itself was a pledge or earnest of a blessed inheritance.

Therefore, being driven into captivity, the people appeared to have been cut off and banished from the presence of God. They had no sign of divine assistance, unless the Lord had soothed their affliction with those promises.

Now, we should carefully observe this distress: when they had been banished into a distant country, they had no temple, or sacrifices, or religious assemblies.

For those who in the present day have no form of a Church, no use of sacraments, and no administration of the word, should consider themselves as being in some measure cast out from the presence of God, and should learn to desire, and continually to ask by earnest prayer for, the restoration of the Church.