Guilt is spoken of as something that can be stored for later use. Here "to pay" refers to punishment for sin. Alternate translation: "God keeps a record of a person's sins, then he punishes the person's children for his wicked deeds" (See: [[rc://en/ta/man/translate/figs-metaphor]])
Job now begins to state his own opinion. It may be helpful to state this explicitly using an indirect quotation. "But I say that he should pay it himself, ... know his guilt'" (See: [[rc://en/ta/man/translate/figs-explicit]])