Musnad Ahmad 27:140

Sufyan narrated to us, he said: Amr heard Sa’id ibn Jubayr saying: I heard Ibn Umar saying: The Messenger of Allah (ﷺ) said to the two who are performing li’an (mutual cursing): "Your reckoning is with Allah. One of you is a liar. You have no way [to claim authority] over her." He said: "O Messenger of Allah, what about my wealth [the dowry I paid]?" He said: "You have no wealth [to reclaim]. If you spoke the truth about her, then it is because of what you made lawful of her private parts. And if you lied about her, then that is further away from you."