Luke 23:17
(For of necessity he must release one unto them at the feast.)
Cross-references
Matthew 27:15
Parallel
Matthew 27:15 describes the same Passover release custom that Luke 23:17 records as obligatory, providing parallel background.
Mark 15:6
Parallel
Mark 15:6 also mentions the custom of releasing a prisoner at the feast, matching Luke's note about the obligation.
John 18:39
Parallel
John 18:39 records the same Passover release custom, which Pilate attempts to use for Jesus' release here.