In other words, when you ask them whether they accept you as the true Nabi of Allah Ta‘ala or not, then they will refer to me and say that they will accept whatever I say. Hence, when they say so, then you should appoint me as the mediator between you and them.

Rasulullah (sallallahu ‘alaihi wasallam) made Hazrat Maymoon (radhiyallahu ‘anhu) conceal himself in a room and sent someone to call the Jews. When they appeared before him, Rasulullah (sallallahu ‘alaihi wasallam) said to them, “Appoint someone to act as a mediator between us.” They replied, “We are pleased to appoint Maymoon bin Yaameen as our mediator. We will gladly accept whatever decision he makes.”

Rasulullah (sallallahu ‘alaihi wasallam) then called out to Hazrat Maymoon (radhiyallahu ‘anhu) saying, “Maymoon! Come out!” As he came out, he declared, “I testify that he is the messenger of Allah.” However, the Jews still refused to accept and believe.

(Extracted from Seeratul Mustafa 1/417-418)