It is narrated from Sayyiduna Sahl bin Sa’d Sa’idi (may Allah be pleased with him) that when a man from Banu Ajlan, Sayyiduna ‘Uwaymir, performed li’an with his wife, he said: “O Messenger of Allah! Now if I keep her in my house even after li’an, it would be oppression on my part towards her, therefore she is divorced, divorced, divorced.” In one narration it is stated: He gave her three divorces even before the command of the Prophet (peace and blessings be upon him). In another narration it is stated: This became the practice among those who performed li’an.
Hadith Referenceالفتح الربانی / كتاب الطلاق / 7159
Benefits: … In this narration, there is no evidence for the immediate effect of three divorces (talaq) at once, because through li'an the marriage is automatically terminated, and there remains no need for divorce. The explanation of li'an will come later. Whereas, it has already been established from the aforementioned narration that during the blessed era of the Prophet sallallahu alayhi wa sallam, three divorces were counted as one. From this, it is understood that although three divorces (talaq) were pronounced, the effect was that of a single divorce.