Jamieson, Fausset and Brown on Mark 14:61

61. But he held his peace, and answered nothing--This must have nonplussed them. But they were not to be easily baulked of their object.

Again the high priest--arose (Mt 26:62), matters having now come to a crisis.

asked him, and said unto him, Art thou the Christ, the Son of the Blessed?--Why our Lord should have answered this question, when He was silent as to the former, we might not have quite seen, but for Matthew, who says (Mt 26:63) that the high priest put Him upon solemn oath, saying, "I adjure Thee by the living God, that Thou tell us whether Thou be the Christ, the Son of God." Such an adjuration was understood to render an answer legally necessary (Le 5:1). (Also see on Joh 18:28.)