(For of necessity he must release one unto them at the feast.) For of necessity he must release one - That is, he was under the necessity of releasing one at this feast. The custom, however it originated, had now been so completely established that Pilate was obliged to attend to it. See on Matthew 27:15 (note).
Related Commentaries of Luke 23:17
Luke 23:17
17 (For of necessity he must release one unto them at the feast.)