Abu Salama bin 'Abdur Rahman أبو سلمة بن عبد الرحمن بن عوف · The Chapters on Legal Punishments

“Whoever has intercourse with a Mahram relative, kill him; and whoever has intercourse with an animal, kill him, and kill the animal.”

“O Messenger of Allah (ﷺ) if a man finds another man with his wife, should he kill him?” The Messenger of Allah (ﷺ) said: “No.” Sa'd said: “Yes he should, by the one who honored you with the Truth!” The Messenger of Allah (ﷺ) said: “Listen to what your leader says!”