15:2

He removes every branch in me that does not produce fruit, and he prunes every branch that does produce fruit, to make it produce more fruit.

There are plays on words in the Greek that cannot easily be reproduced in English'; 'he removes' is airei and 'he prunes' is kathairei. Moreover, kathairei can also mean ' he cleanses' and is linked with 'clean' in verse 3: 'you are kathairei. Here is an echo of John 13:10, 'you are clean (kathoaroi), but not all'. Judas was the exception then; in terms of the present parable, he is an unfruitful branch that has to be removed.

The Gospel of John, F.F. Bruce p.308