Don't carry it into tomorrow
"“In your anger do not sin”: Do not let the sun go down while you are still angry, and do not give the devil a foothold."
— Ephesians 4:26-27
The lines on either side are practical orders: stop lying to each other just before, and whoever has been stealing should go to work with his hands just after. These are rules for people who lived close together and could not get away from each other, not advice about managing a mood. The opening words in quotation marks are not Paul's own. They match the Greek version of Psalm 4 word for word, and in Greek they are a command rather than a ban, so the feeling itself is left standing. The Hebrew behind that psalm line leans closer to tremble, which is why some Bibles read quite differently at that spot. The term behind 'foothold' is the ordinary Greek word for a place or a room, and it was also used for the opening you hand someone to act. The sunset line is read two ways, as a real deadline or as a common saying that meant settle it fast. The Jewish day ran from evening to evening, so on either reading the window is hours rather than weeks. Anger left overnight stops being something you feel and becomes something you live with.