Walled cities in the apostle’s time posted sentries at its gates by day to guard access to the city. By night, however, the gates were typically shut (and locked) so that no one could enter or leave. In the event of danger, gates were also shut during daylight hours. It was all a matter of security. In the New Jerusalem, however, the gates will never be shut “by day.” The implication is that there would never be a threat to the inhabitants’ safety. The consequence is that traffic and trade will enter and leave at will, including the glory of kings.
25 and its gates will never be shut by day and there will be no night there.