The psalmist describes the joy and beauty of brothers dwelling in unity, comparing it to the anointing oil on Aaron's head and the dew on Mount Hermon, which both flow down and bring life. This unity is a blessing from the Lord that brings life and eternity.
1 A Canticle in steps: of David. Behold, how good and how pleasing it is for brothers to dwell in unity 2 It is like the ointment on the head that descended to the beard, the beard of Aaron, which descended to the hem of his garment 3 It is like the dew of Hermon, which descended from mount Zion. For in that place, the Lord has commanded a blessing, and life, even unto eternity