Obedience
Jeremiah is writing to the people of Israel when they are about to be destroyed for disobeying God. The Rechabites are a family that refuses to drink wine based on a command from one of their ancestors. God is pointing out a contrast between a group of people who obeyed a human-made rule and the nation that refused to obey God.
Do we take human-made rules more seriously than God鈥檚 rules? We obey speed limits and pay our taxes out of fear of punishment, but do we ignore God鈥檚 rules because He seems far off or unlikely to punish us? God鈥檚 power and love should move us to obedience.