Abul-Mukhariq Zuhair bin Salim narrated that `Umair bin Sa`d al-Ansari was appointed by `Umar as governor of Hims... and he mentioned the hadeeth `Umar said to Ka`b:
I am going to ask you about something, so do not hide it from me. [Ka`b said: By Allah I will not hide anything I know. ‘Umar said: What do you fear most for the ummah of Muhammad (ﷺ)? He said: Misleading leaders. `Umar said: The Messenger of Allah (ﷺ) told me about that in private and informed me of it.