Ali said, "They once beat the Messenger of Allah ﷺ until he lost consciousness. Abu Bakr stood up and began crying out, 'Woe to you! Would you kill a man merely because he says, My Lord is Allah?' [Ghafir 40:28]"They asked, "Who is this?"Someone replied, "It is the madman, the son of Abu Quhafa."
لقد ضربوا رسول الله ﷺ مرة حتى غشي عليه. فقام أبو بكر فجعل ينادي: ويلكم {أتقتلون رجلا أن يقول ربي الله} [ غافر: ٢٨] فقالوا: من هذا؟ قال: ابن أبي قحافة المجنون.
Abu Yaala (3691) and Hakim (3/67) both narrated it from the hadith of Muhammad bin Abdullah bin Numayr, who said, Ibn Abu Ubayda told us, my father told me, from Abu Sufyan, from Anas bin Malik, who related it. Its chain is sahih. Hakim said, "Sahih according to the criterion of Muslim." Hafiz also declared it sahih in Fath al-Bari (7/169). It has a corroborating narration from the hadith of Asma bint Abu Bakr recorded by Abu Yaala (52), and from the hadith of Ali recorded by Bazzar (2481), though in both of their chains there is someone unknown.