Who has the public's approval to judge?

Hawzah News Agency- Muhammad ibn Ali Majiluyih narrated that his uncle Muhammad ibn Abil-Qasim narrated from Ahmad ibn Aba Abdullah, from Al-Hassan ibn Mahboob, from some of the companions that Imam Sadiq (pbuh) said:

من أنصف الناس من نفسه رضي به حكما لغيره

Whoever deals justly with people with respect to himself, people will be content to accept him as a judge over others.

Al-Khisal,Book 2,Chapter 19