Prayer for unity, as the people journeyed, from as far as Hermon in the north, to Jerusalem.
v1: Unity amongst brothers. We are to dwell together, with an attitude of agreement and humility, believing and sharing together. The literal meaning here is to 'sit together', as in Ps 1.1. Such unity is not automatic; it demands an effort to promote unity, and to put away critical or divisive attitudes.
v2: The precious oil of anointing, Ex 30.22-33, by which the High Priest was sanctified. Such is the effect of unity. The picture is also of the anointing of the Holy Spirit, bringing us into relationship together, and equipping us to serve. The once-only experience pictured here is balanced by the daily blessing of the dew, in v3.
v3: Blessing from God, as dew, something daily. Life in God is eternal life.