Charles Ellicott Commentary John 18:16

"but Peter was standing at the door without. So the other disciple, who was known unto the high priest, went out and spake unto her that kept the door, and brought in Peter." — John 18:16 (ASV)

But Peter stood at the door without.—i.e., at the door of the court. He remained here with the crowd. Jesus as a prisoner, and the other disciple as a friend of the high priest, went into the court.

Unto her that kept the door.—Compare to Acts 12:13 and 2 Samuel 4:6 (LXX.). That women “kept the door” among the Jews we know from Josephus (Antiquities vii. 2, § 1).