Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
bukhari:7157ʿAbdullāh b. al-Ṣabbāḥ > Maḥbūb b. al-Ḥasan > Khālid > Ḥumayd b. Hilāl > Abū Burdah > Abū Mūsá > a man Aslam Thum Tahawwad Faʾatá Muʿādh b. Jabal And Hw ʿInd Abū Mūsá > Mā Hadhā > Aslam Thum Tahawwad

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

البخاري:٧١٥٧حَدَّثَنِي عَبْدُ اللَّهِ بْنُ الصَّبَّاحِ حَدَّثَنَا مَحْبُوبُ بْنُ الْحَسَنِ حَدَّثَنَا خَالِدٌ عَنْ حُمَيْدِ بْنِ هِلاَلٍ عَنْ أَبِي بُرْدَةَ عَنْ أَبِي مُوسَى أَنَّ رَجُلاً أَسْلَمَ ثُمَّ تَهَوَّدَ فَأَتَى مُعَاذُ بْنُ جَبَلٍ وَهْوَ عِنْدَ أَبِي مُوسَى فَقَالَ مَا هَذَا قَالَ أَسْلَمَ ثُمَّ تَهَوَّدَ قَالَ

لاَ أَجْلِسُ حَتَّى أَقْتُلَهُ قَضَاءُ اللَّهِ وَرَسُولِهِ ﷺ