(And Allah wishes to turn to you in mercy) He wishes to overlook your transgression when He made adultery and marrying your sisters, from the father's side, forbidden for you; (but those who follow vain desires) i.e. adultery and marrying their sisters from their fathers' side, namely, the Jews (would have you go tremendously astray) commit a serious error by marrying your sisters, from the father's side, by claiming that it is lawful in their Scripture.