The Harmony Of The Gospels by St. Augustine
Chapter XIV.--Of the Harmony Preserved Among All the Evangelists on the Subject of the Two Robbers Who Were Crucified Along with Him.
51. Matthew continues his narrative in the following terms: |Then were there two robbers crucified with Him, one on the right hand, and another on the left.| Mark and Luke give it also in a similar form. Neither does John raise any question of difficulty, although he has made no mention of those robbers. For he says, |And two other with Him, on either side one,and Jesus in the midst.| But there would have been a contradiction if John had spoken of these others as innocent, while the former evangelists called them robbers.