A.T. Robertson Commentary Matthew 20:13

"But he answered and said to one of them, Friend, I do thee no wrong: didst not thou agree with me for a shilling?" — Matthew 20:13 (ASV)

To one of them (εν αυτων). Evidently the spokesman of the group. "Friend" (εταιρε). Comrade. So a kindly reply to this man in place of an address to the whole gang. Genesis 31:40; Job 27:21; Hosea 13:15. The word survives in modern Greek.