Repeated in all three evangelists, in the narratives both of the betrayal and of the arrest. By the time Matthew's Gospel was written, the phrase had become a stereotyped designation of the traitor, like he that betrayed him.
A great multitude
The Sanhedrin had neither soldiery nor a regularly-armed band at command. In Joh 18:3, Judas receives a cohort of soldiers and officers from the chief priests and Pharisees. Part of the band would consist of this regularly-armed cohort, and the rest of a crowd armed with cudgels, and embracing some of the servants of conspicuous men in the Sanhedrin.