The term is often used in a context of temple sacrifice; the cry, Be silent before the Lord GOD!
was the priestly cry to reverential silence before the sacrifice was made.1 The command to silence here clearly has such a sacrificial setting. It implies the imminence of the Lord himself. Standing before his awesome majesty on his great day inspires the most humble and reverent demeanor.
2
7 Be silent before the Lord GOD! For the day of the LORD is near; the LORD has prepared a sacrifice and consecrated his guests.