Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: Whoever denies the punishment of stoning has denied the Most Merciful, and Allah Almighty has said: "O People of the Book! Our Messenger has come to you, clarifying to you much of what you used to hide from the Book, and overlooking much." (Sayyiduna Ibn Abbas, may Allah be pleased with him, narrates) So among the things they used to hide was the punishment of stoning.