Musnad Ahmad 4341

It was narrated that 'Abdullah bin Mas'ood said: Whilst we were walking with the Messenger of Allah (ﷺ), he passed by some boys who were playing, anong whom was Ibn Sayyad. The Messenger of Allah (ﷺ) said: "May your hands be rubbed with dust, do you bear witness that I am the Messenger of Allah?" He said: Do you bear witness that I am the messenger of Allah? 'Umar (رضي الله عنه) said: Let me strike his neck. The Messenger of Allah (ﷺ) said: “If he is the one you fear he is, you will not be able to harm him.”