A.T. Robertson Commentary Matthew 20:17

"And as Jesus was going up to Jerusalem, he took the twelve disciples apart, and on the way he said unto them," — Matthew 20:17 (ASV)

Apart (κατ' ιδιαν). This is the prediction in Matthew of the cross (16:21; 17:22; 20:17). "Aside by themselves" (Moffatt). The verb is παρελαβεν. Jesus is having his inward struggle and makes one more effort to get the Twelve to understand him.