This comes in here as a token of God's displeasure at those who married strange wives; he threatens to withdraw from them his Spirit, whom they had grieved by such marriages, contrary to their convictions: fleshly lusts are often punished with spiritual judgments, the sorest of all judgments. Or as another occasion of the great wickedness of the old world; the Spirit of the Lord, being provoked by their resistance of his motions, ceased to strive with them, and then all religion was soon lost among them. This he warns them of before, that they might not further vex his Holy Spirit, but by their prayers might stay him with them. Observe in this verse,
I. God's resolution not always to strive with man by his Spirit. The Spirit then strove by Noah's preaching (1 Pet. iii. 19, 20) and by inward checks, but it was in vain with the most of men; therefore, says God, He shall not always strive. Note, 1. The blessed Spirit strives with sinners, by the convictions and admonitions of conscience, to turn them from sin to God. 2. If the Spirit be resisted, quenched, and striven against, though he strive long, he will not strive always, Hos. iv. 17. 3. Those are ripening apace for ruin whom the Spirit of grace has left off striving with.
II. The reason of this resolution: For that he also is flesh, that is, incurably corrupt, and carnal, and sensual, so that it is labour lost to strive with him. Can the Ethiopian change his skin? He also, that is, All, one as well as another, they have all sunk into the mire of flesh. Note, 1. It is the corrupt nature, and the inclination of the soul towards the flesh, that oppose the Spirit's strivings and render them ineffectual. 2. When a sinner has long adhered to that interest, and sided with the flesh against the Spirit, the Spirit justly withdraws his agency, and strives no more. None lose the Spirit's strivings but those that have first forfeited them.
III. A reprieve granted, notwithstanding: Yet his days shall be one hundred and twenty years; so long I will defer the judgment they deserve, and give them space to prevent it by their repentance and reformation. Justice said, Cut them down; but mercy interceded, Lord, let them alone this year also; and so far mercy prevailed, that a reprieve was obtained for six-score years. Note, the time of God's patience and forbearance towards provoking sinners is sometimes long, but always limited: reprieves are not pardons; though God bear a great while, he will not bear always.