The Geneva Bible Translation Notes, , at sacred-texts.com
psa 133:1"A Song of degrees of David." Behold, how good and how pleasant [it is] for brethren to dwell (a) together in unity!
(a) Because the greatest part was against David, though some favoured him, yet when he was established king at length, they joined all together like brothers: and therefore he shows by these similarities the convenience of brotherly love.
psa 133:2[It is] like the precious (b) ointment upon the head, that ran down upon the beard, [even] Aaron's beard: that went down to the skirts of his garments;
(b) The ointment was a figure of the graces which come from Christ the head of his Church.
psa 133:3As the dew of (c) Hermon, [and as the dew] that descended upon the mountains of Zion: for (d) there the LORD commanded the blessing, [even] life for evermore.
(c) By Hermon and Zion he means the plentiful country about Jerusalem.
(d) Where there is such concord.