It is narrated from Abu Hurairah (may Allah be pleased with him) that Sa'd (bin 'Ubadah, may Allah be pleased with him) said: "O Messenger of Allah (ﷺ)! If I find a man with my wife, should I wait until I bring four witnesses?" The Messenger of Allah (ﷺ) said: "Yes."
Hadith Referenceمسند الإمام الشافعي / كتاب القضاء والأحكام والدعاوى والبينات واليمين ومع الشاهد والأيمان والشهادات / 1699