The Gate of the Ruler

[Umm]

Assalaamu Alaikum,
Can anyone find me the hadith with a reference [I am pretty sure it is a hadith] that reads,
"Beware of the scholar that sits at the gate of the ruler?"
wa-salaam,
Umm.

[tawakkal]

sa wr wb

http://www.islamicweb.com/beliefs/creed/sultan_scholars.htm

ws wr wb