Sayyiduna Mudrik (may Allah be pleased with him) narrates: I performed Hajj with my father. When we had camped at Mina, there were some people gathered there. I asked my father: "Why have these people gathered?" He told me: "This is a man who has turned away from his religion." And there was the Prophet (peace and blessings be upon him) saying: "O people! Say La ilaha illallah (there is no god but Allah) and you will be successful."
Al-Tabarani recorded it, and its narrators are thiqat (trustworthy).