Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: Previously, when a woman committed adultery she would be confined in the house, and when a man committed adultery he would be reproached and beaten with shoes. Then Allah Almighty revealed this verse of Surah al-Nur: "The woman and the man guilty of fornication, flog each one of them with a hundred lashes" [Surah al-Nur: 2]. If they were married, they would be stoned according to the Sunnah of the Prophet (peace and blessings be upon him), and this is the way that Allah has appointed for them.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحدود / 16914