Mohammad bin Abdillah bin Abdil Muttaleb bin Matar Al-Shaibani narrated from Abdullah bin Saeed, from Moammal bin Ahaab, from Abdul Razzaq, from Mo’ammar, from Al-Zohari, from Urwah, from Ayesha (LA), who said:
ALI BIN ABI TALEB (ASWS) came to my father (abu bakr (LA)) while he was ill with the illness that caused his death. My father was staring at his (ALI (ASWS) ’s) face and would not take his eyes off of him.
So when ALI BIN ABI TALEB (ASWS) left, I asked my father, “Why were you looking at his face like that?”
He (abu bakr (LA)) replied, “Because I heard the MESSENGER OF ALLAH (SWT) say, ‘Looking at the face of ALI (ASWS) is worshipping ALLAH (SWT).”
(Ref : Bihr Volume 26 Page 229 Hadees 11)