Nafi' narrates from Abdullah bin Umar (may Allah be pleased with them both) that in the time of the Messenger of Allah (peace and blessings be upon him) a man accused his wife and denied his child. The Messenger of Allah (peace and blessings be upon him) commanded them to perform li'an, and they performed li'an just as Allah, the Lord of Might, had said. He gave judgment that the child belonged to the woman and separated the two who performed li'an.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب اللعان / 15341