John Goldingay’s translation of Psalm 133 (Hebrew text provided) with select comments from his theological observations:
הנה מה־טוב ומה־נעים
שׁבת אחים גם־יחד
Now: How good and how lovely
is kinfolk living as one
כשׁמן הטוב על־הראשׁ
Like Good oil upon the head,
going down upon the beard,
Aarons beard, which goes down
upon the collar of his clothing.
כי שׁם צוה יהוה את־הברכה
Like the dew of Hermon, which goes down
upon the mountains of Zion
Because there Yhwh commanded the blessing,
life for evermore.
The presence of this Psalm in the Psalter, and the particular terms in which it speaks, reminds the community how significant for the worshipping community is living as one. . . . The most spectacularly unanswered prayer in world history is Jesus’s prayer in John 17:20-23. Christian kinfolk live in breathtaking disharmony. This devastates their witness as it removes the goodness and the loveliness from them; it removes their joy and surrenders their blessing.The psalm invites us to consider the loveliness of kinfolk living as one and to meditate on the images for this that it offers, to see if this inspires us to live as one.
Goldingay, John. Psalms, Vol 3. Baker Exegetical Commentary on the Old Testament (Grand Rapids: Baker Academic, 2008) 563-9