John 12:34

The people answered Him, We have heard out of the Law, that Christ abideth ever, and how sayest Thou, the Son of Man must be lifted up? The Jews understood that Christ spake of His death on the Cross. How then does He say that He would die, when the Law says that He would not die? S. Augustine says, "They understood Him to mean the very thing which they were contemplating. It was not inspired wisdom, but the sting of their conscience which disclosed to them the meaning of these obscure words."

Out of the Law. By the Law is meant the whole of the Old Testament. They understood this from the following passages, Micah, v. 2; Psa 110:14, Psa 90:30, Psa 90:38, Psalms 72:5; Isaiah 9:7; Isaiah 40:8; Ezekiel 37:27; Daniel 9:26. But these passages speak of the kingdom of Christ after His ascension. This kingdom will be eternal. But Christ elsewhere foretold His death. See Isaiah 53:3; Psalms 22:12; Psalms 22:17; Daniel 9:26; Jeremiah 11:19.

Who is this Son of Man? Meaning thereby, "If Thou art that Son of Man, as Thou art wont to call Thyself, how dost Thou wish to be regarded as the Christ? For Christ according to the Scriptures, as has just been said, is eternal, and cannot die. Whereas Thou sayest, on the contrary, that the Son of Man must die and be raised up on the Cross. If there be any other Son of Man, tell us plainly who he is.". So Toletus and Jansen. Maldonatus somewhat differently; he thinks that the Jews insulted Christ as if they had refuted His claims, and taunted Him, as a conqueror would taunt a king whom he had taken captive. As the Jews afterwards said (tauntingly) to Him, "Hail, King of the Jews!"