It was
narrated that Abu Sa’eed said:
“The Messenger of Allah (ﷺ)
came
out to us when we were discussing Dajjal (False Christ) and said:
‘Shall I not tell you of that which I fear more for you than
Dajjal?’
We said: ‘Yes.’ He said: ‘Hidden polytheism, when a
man stands to pray
and makes it look good because he sees a man
looking at him.’”