Matthew 26:63 - Ellicott's Commentary On The Whole Bible

I adjure thee by the living God ... — The appeal was one of unusual solemnity. All else had failed to break through the silence, but this would surely rouse Him. Technically, the oath thus tendered to the accused was of the nature of an oath of compurgation, such as that recognised in Exodus 22:11; Numbers 5:19-22; 1 Kings 8:31, but it was skilfully worded so as to force upon our Lord the alternative either of denying what indeed He was, or of making a confession which would be treated as blasphemy. The records of St. John’s Gospel (John 5:18; John 8:58; John 9:37; John 10:24) show us that they had good means of knowing what answer to expect.