The pilgrim then asked God to bless these special servants of His. The reference to God being the Maker of heaven and earth recalls His greatness (cf. Psalm 115:15; et al.). This verse is also an appropriate conclusion to the collection of ascent psalms ( Psalm 120-134). [source][source][source]
Context Summary
Psalms 134:1-3 - Unity Is Of God
The word Behold suggests that some special manifestation of unity was taking place under the psalmist's eyes, perhaps in connection with some great religious festival; or David may have composed it to celebrate the healing of the breach after the death of Ishbosheth. We must not only be one in God's purpose, but must be willing to dwell together, that is, to manifest our unity in outward action. For the precious oil see Exodus 30:20-38 and 1 John 2:27. Our Lord was anointed with the Holy Spirit, and we may share in His Pentecost, Luke 3:21-22; Acts 2:33.
Psalms 134:1-3. The last of the "Songs of Degrees." It may have been addressed to the priests who came on duty after the offering of the evening sacrifice. There was evidently a band of choristers and others who were on duty while Jerusalem slept. The psalm ends with the reciprocal blessing of the watchers on the retreating crowds; commending them, during the hours of darkness, to the care of the Lord of heaven and earth. [source]