John 8:21
“Then said Jesus unto them, I go My way, and you shall seek Me.”
Why says He this continually? To shame and terrify their souls; for observe what fear this saying caused in them. Although they desired to kill Him that they might be rid of Him, they yet ask, “whither He goes,” such great things did they imagine from the matter. He desired also to show them another thing, that the deed would not be effected through their force; but He showed it to them in a figure beforehand, and already foretold the Resurrection by these words.
Source: Homilies on the Gospel of John (New Advent)