The Prophet ﷺ said, "Whoever withdraws his hand from obedience will have no defense on the Day of Resurrection, and whoever dies having separated from the community dies the death of pre-Islamic ignorance."
حدثنا حسن حدثنا عبد الرحمن بن عبد الله يعني ابن دينار عن زيد بن أسلم
عن النبي ﷺ قال من نزع يدا من طاعة فلا حجة له يوم القيامة ومن مات مفارقا للجماعة فقد مات ميتة جاهلية
Its isnad is sahih. It will come again at 5676 through Muhammad bin Ajlan, from Zayd bin Aslam, from Ibn Umar, in similar wording. It will also come again at 5551 within a story, through Hisham bin Saad, from Zayd bin Aslam, from his father, from Ibn Umar. Muslim likewise narrated it in similar wording, at greater length, 2:90, through Hisham bin Saad, from Zayd bin Aslam, from his father, from Ibn Umar.It appears, then, that Zayd bin Aslam did not witness the story that his father witnessed. He narrated it from his father, with the hadith included within it, but he heard the hadith itself alone from Ibn Umar, and so narrated it from him directly without an intermediary. Muslim also narrated it, 2:89–90, at greater length within the story, through two isnads, both through Nafi, from Ibn Umar. See also what has already appeared in the Musnad of Ibn Abbas, 2826 and 2827. Ibn Kathir also mentioned it in his tafsir, 2:495, from Muslim's narration.