Praise be to Allah,
Sufyaan ibn Uyaynah narrated to us from [Muhammad ibn Shihaab] az-Zuhree from Anas ibn Maalik who said;
“The last glance I cast at Allah’s was on a Monday when he drew aside the curtain [of(Aa’ishah’s apartment] while the people were praying behind Abu Bakr. I [looked at] his face and I saw that it was [as bright as] the page of the Holy Book. The people wanted to move [as they thought he was going to join the prayer], but he motioned to them [to attend to their prayer]. Then he drew the curtain, and he passed away towards the end of that very day.”
(Musnad Ahmad, Vol. 3, p. 110. The isnaad of this hadeeth is Saheeh according to the conditions set by al-Bukhari and Muslim.)
Source:
Thulaathiyyaat Musnad Ahmad ibn Hanbal (may Allah have mercy on him)
Reports of Imaam Ahmad that have only three narrators between him and the Prophet, peace, and blessings be upon him.
Shaykh Muhammad ibn Ahmad ibn Saalim as–Saffaareenee al–Hanbalee ~(1114 –1188 AH)