Live together in unity

Psalm 133:1-3
How good and pleasant it is when brothers live together in unity.
It is like precious oil poured on the head, running down on Aaron's beard.
It is as if the dew of Hermon were falling on Mount Zion.
For there the Lord bestows his blessing, even life forevermore.
This is a 'wisdom' psalm. The theme is the family Harmony of God's people. Precious as holy oil or dwell on bare hills.
Why?
Oil is blessing of the Lord for his work. dew is important nourish of the field, bringing fertility.
Brothers live together in unity has the blessing from the Lord, and life forevermore.
Sons of David got into fights many times, so the kingdom has many trouble and divided.
How?
Family brothers and church brothers shell live together in unity. It shows the honor of the God, shows the Lord of God among us.