Matthew Poole and continuators on Numbers 14:18

18 The LORD is long-suffering, and of great mercy, forgiving iniquity and transgression, and by no means clearing the guilty, visiting the iniquity of the fathers upon the children, unto the third and fourth generation .

These words may seem to be very improperly mentioned, as being a powerful argument to move God to destroy this wicked people, and not to pardon then. It may be answered, that Moses useth these words together with the rest partly because he would not sever what God had put together, and partly to shew that he did not desire a full and absolute pardon, but was willing that God should execute his vengeance upon the principal authours of this rebellion, and leave some character of his displeasure upon all the people, as God did, but onely that God would not disinherit them, ver. 12. nor kill all the people as one man, ver. 15. nor destroy them both root and branch, because he had promised not to extend his wrath against them in punishing their sins beyond the third and fourth generation. But the truer answer seems to be, that these words are to be translated otherwise and in destroying he will not utterly destroy, though he visit the iniquity of the fathers upon the children, unto the third and fourth generation. Of which see the notes on Exod. 34. 7. where all this verse is explained.

Marginal references: Exod. 34. 6. Psal. 103. 8.; Exod. 20. 5. and 34. 7.