(1) باب مِنْ فَضَائِلِ أَبِي بَكْرٍ الصِّدِّيقِ رضى الله عنه
A'isha reported that Allah's Messenger (ﷺ) in his (last) illness asked me to call Abu Bakr, her father, and her brother too, so that he might write a document, for he feared that someone else might be desirous (of succeeding him) and that some claimant may say:
I have better claim to it, whereas Allah and the Faithful do not substantiate the claim of anyone but that of Abu Bakr.
Reference: Sahih Muslim 2387
In-book reference: Book 44, Hadith 12
USC-MSA web (English) reference(deprecated numbering scheme): Book 31, Hadith 5879