Sahih al-Bukhari Book 86, Hadith 81
A man came to the Prophet (ﷺ) and said, "I beseech you to judge us according to Allah's Laws." Then his opponent who was wiser than he, got up and said, "He has spoken the truth. So judge us according to Allah's Laws and please allow me (to speak), O Allah's Messenger (ﷺ)." The Prophet (ﷺ) said, "Speak." He said, "My son was a laborer for the family of this man and he committed illegal sexual intercourse with his wife, and I gave one-hundred sheep and a slave as a ransom (for my son), but I asked the religious learned people (regarding this case), and they informed me that my son should be flogged onehundred stripes, and be exiled for one year, and the wife of this man should be stoned (to death)."The Prophet (ﷺ) said, "By Him in Whose Hand my soul is, I will Judge you (in this case) according to Allah's Laws. The one-hundred (sheep) and the slave shall be returned to you and your son shall be flogged one-hundred stripes and be exiled for one year. And O Unais! Go in the morning to the wife of this man and ask her, and if she confesses, stone her to death." She confessed and he stoned her to death.
I heard Abu-l-Qasim (the Prophet) saying, "If somebody slanders his slave and the slave is free from what he says, he will be flogged on the Day of Resurrection unless the slave is really as he has described him."
A man said, "O Allah's Messenger (ﷺ)! Which sin is the greatest in Allah's Sight?" The Prophet (ﷺ) said, "To set up a rival unto Allah though He Alone created you . " The man said, "What is next?" The Prophet (ﷺ) said, "To kill your son lest he should share your food with you." The man said, "What is next?" The Prophet said, "To commit illegal sexual intercourse with the wife of your neighbor." So Allah revealed in confirmation of this narration:-- 'And those who invoke not with Allah, any other god. Nor kill, such life as Allah has forbidden except for just cause nor commit illegal sexual intercourse. And whoever does this shall receive the punishment.' (25.68)