Here and in verse 5 Judas is introduced as the traitor. This epithet (literally “the man betraying him”) is similar to the designation of Judas in 6.64 (which one would betray him) and 6.71 (Judas … was going to betray him). Although Judas was spoken of as the betrayer three times in chapter 13 (verses 2,11, and 21), the information is not redundant at the beginning of Chapter 18, since the passion narratives were probably the first part of the gospel to circulate independently.

An equivalent of the term traitor may suggest a conspirator against the state or one who betrays state secrets, rather than one who betrays a friend. It may therefore be more appropriate to use such a descriptive expression as “the one who turned Jesus over to his enemies” or “the one who betrayed Jesus.” Judas was, in a sense, cooperating with the civil authorities, and hence a more or less literal translation of traitor could be misleading.

Knew where it was is literally “knew the place” (Jerusalem Bible “knew the place well”).

Instead of the statement Jesus had met there with his disciples, it is appropriate in some languages to say “Jesus and his disciples had met there.” A literal translation might suggest that the disciples had gathered in the garden, and that Jesus surreptitiously joined them.

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on the Gospel of John. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .