When Uthman was about to be killed, Abdullah bin Salam came to him.Uthman asked him, "What brings you here?"He replied, "I came to support you."Uthman said, "Go out to the people and turn them away from me, for you outside are of more benefit to me than you inside."So Abdullah bin Salam went out to the people and said, "People, my name in the days of ignorance was so-and-so, then the Messenger of Allah ﷺ named me Abdullah. Verses from the Book of Allah were revealed concerning me, 'And a witness from the Children of Israil testified to something similar, and he believed while you were arrogant. Indeed, Allah does not guide the wrongdoing people' [Ahqaf 46:10], and there was also revealed concerning me, 'Say, sufficient is Allah as a witness between me and you, and whoever has knowledge of the Scripture' [Rad 13:43]. Allah has a sword that is sheathed from you, and the angels have become your neighbors in this city of yours in which your Prophet was sent. So fear Allah, fear Allah regarding this man, do not kill him. By Allah, if you kill him, you will drive away your neighbors the angels, and the sword of Allah that is sheathed from you will be drawn and will not be sheathed again until the Day of Resurrection."They said, "Kill the Jew, and kill Uthman."
حدثنا علي بن سعيد الكندي حدثنا أبو محياة عن عبد الملك بن عمير
لما أريد عثمان جاء عبد الله بن سلام فقال له عثمان ما جاء بك قال جئت في نصرك قال اخرج إلى الناس فاطردهم عني فإنك خارج خير لي منك داخل فخرج عبد الله بن سلام إلى الناس فقال أيها الناس إنه كان اسمي في الجاهلية فلان فسماني رسول الله ﷺ عبد الله ونزل في آيات من كتاب الله نزلت في {وشهد شاهد من بني إسرائيل على مثله فآمن واستكبرتم إن الله لا يهدي القوم الظالمين} ونزلت في {قل كفى بالله شهيدا بيني وبينكم ومن عنده علم الكتاب} إن لله سيفا مغمودا عنكم وإن الملائكة قد جاورتكم في بلدكم هذا الذي نزل فيه نبيكم فالله الله في هذا الرجل أن تقتلوه فوالله إن قتلتموه لتطردن جيرانكم الملائكة ولتسلن سيف الله المغمود عنكم فلا يغمد إلى يوم القيامة قال فقالوا اقتلوا اليهودي واقتلوا عثمان
Its isnad is daif. Ibn Majah narrated it in the chapter on changing names, hadith no. 3734, from the hadith of Abu Mihyah, in a shortened form.The nephew of Abdullah bin Salam has not been deemed reliable by anyone other than Tirmidhi, as far as I know, so he is majhul (of unknown status).The hadith of Abdul-Malik bin Umayr was narrated by Tabarani (Majma al-Zawaid, 9/92, 93). See also Jami al-Masanid wal-Sunan by Ibn Kathir, 8/65.