Narrated Abu Musa: A man embraced Islam and then reverted back to Judaism. Mu`adh bin Jabal came and saw the man with Abu Musa. Mu`adh asked, What is wrong with this (man)? Abu Musa replied, He embraced Islam and then reverted back to Judaism. Mu`adh said, I will not sit down unless you kill him (as it is) the verdict of Allah and His Apostle.