Al-Ma'idah 5:107

Fa-in AAuthira AAala annahumaistahaqqa ithman faakharani yaqoomanimaqamahuma mina allatheena istahaqqaAAalayhimu al-awlayani fayuqsimani billahilashahadatuna ahaqqu min shahadatihimawama iAAtadayna inna ithan lamina aththalimeen

But if it is found that those two were guilty of sin [i.e., perjury], let two others stand in their place [who are] foremost [in claim] from those who have a lawful right. And let them swear by Allāh, "Our testimony is truer than their testimony, and we have not transgressed. Indeed, we would then be of the wrongdoers."

Then, if it is discovered that the two had rendered themselves liable to a sin, then, in their place shall stand two others, closest of those whose right has been taken away, and they shall swear by Allah, “Our evidence is more truthful than their evidence, and we have not transgressed; otherwise we should be among the unjust.”