A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
psa 134:21-2. The pilgrim bands arriving at the sanctuary call on the priests, who (Psa 134:1-3)
Lift up your hands--(Compare Psa 28:2).
psa 134:3After the manner directed (Num 6:23).
out of Zion--the Church, as His residence, and thus seat of blessings. Thus close the songs of degrees.