Passage
The disciples therefore looked one on another, doubting of whom he spoke.
The disciples therefore looked one on another, doubting of whom he spoke.
John 13:20 Verily, verily, I say to you, He who receives whomsoever I shall send receives me; and he that receives me receives him who has sent me.
John 13:21 Having said these things, Jesus was troubled in spirit, and testified and said, Verily, verily, I say to you, that one of you shall deliver me up.
John 13:22 The disciples therefore looked one on another, doubting of whom he spoke.
John 13:23 Now there was at table one of his disciples in the bosom of Jesus, whom Jesus loved.
John 13:24 Simon Peter makes a sign therefore to him to ask who it might be of whom he spoke.
The verse centers on "disciples", "therefore", "looked", "another", "doubting", and "spoke". It is saying that the verse draws attention to "disciples" and "therefore", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 21's "Having said these things Jesus was troubled..." into verse 23's "Now there was at table one of...", so "disciples" and "therefore" belong inside that flow. In John context, the local focus is the identity of Jesus, new birth, eternal life, and belief and unbelief.
A plain takeaway is to answer the verse's own emphasis on "disciples" and "therefore" with trust shaped by these words, not by a vague optimism outside the passage.