Keeping mercy for thousands, forgiving iniquity and transgression and sin, and that will by no means clear the guilty; visiting the iniquity of the fathers upon the children, and upon the children’s children, unto the third and to the fourth generation.
God's mercy lasts forever, but He forgives people's wrongdoings and sins, yet this won't completely free those who are guilty. He passes the punishment for sin from parents to their children and even to their grandchildren, up to the third and fourth generations.