The Prophet ﷺ sent him to Yemen, and afterward sent Muaz bin Jabal as well. When Muaz arrived, he said, "People, I am a messenger sent to you from the Messenger of Allah."Abu Musa placed a cushion for him to sit on. Then a man was brought forward who had been a Jew, then embraced Islam, and then renounced his faith.Muaz said, "I will not sit down until he is killed. This is the judgment of Allah and His Messenger." He repeated it three times.Once the man was executed, Muaz sat down.
حدثنا محمد بن بشار وحدثني حماد بن مسعدة قالا حدثنا قرة بن خالد عن حميد بن هلال
أن النبي ﷺ بعثه إلى اليمن ثم أرسل معاذ بن جبل بعد ذلك فلما قدم قال أيها الناس إني رسول رسول الله إليكم فألقى له أبو موسى وسادة ليجلس عليها فأتي برجل كان يهوديا فأسلم ثم كفر فقال معاذ لا أجلس حتى يقتل قضاء الله ورسوله ثلاث مرات فلما قتل قعد
Bukhari narrated it, no. 6923, 7157, and Muslim, no. 15/1733 before, no. 1825, from the hadith of Qurra bin Khalid, at greater length, and it is in Kubra, no. 3529.