Albert Barnes Commentary Jeremiah 37:13

"And when he was in the gate of Benjamin, a captain of the ward was there, whose name was Irijah, the son of Shelemiah, the son of Hananiah; and he laid hold on Jeremiah the prophet, saying, Thou art falling away to the Chaldeans." — Jeremiah 37:13 (ASV)

A captain of the ward — Captain of the watch, whose duty it was to examine all who went in and out.

The gate of Benjamin — The northern gate, also called the gate of Ephraim.

Thou fallest away ... — His well-known views made Jeremiah a suspected person, though the charge was groundless.