Augustine. Exposition on the Book of Psalms. Schaff, Philip (editor). New York: Christian Literature Publishing Co, 1886. Nicene and Post-Nicene Church Fathers: Series 1: Volume VIII. Re-published 2014, Catholic Way Publishing. Kindle electronic edition, ISBN-13: 978-1-78379-372-3.
Commenting on Psalm 121:1, Augustine urges his readers to recognize that when they look to the hills, Christ, the Sun of Righteousness, has risen and thus enlightened the world (Augustine Psalms, loc. 340107, par. 1). The help does not come from the hills, but from Christ.
The Psalm continues with an exhortation not to let your feet be moved. Augustine takes this to be informed by the fact that Satan, as an angel of light, allowed his feet to be moved by pride, thus falling (Augustine Psalms, loc. 340111, par. 2). The exhortation then is to walk as humble people before God. The prayer continues that God would show himself as the one who never sleeps. Trusting in him will allow us to rest (Augustine Psalms, loc. 340123, par. 3). Verse five describes God on the right hand of the believer. Augustine ties this to the Gospel statement of not allowing your left hand to know what your right hand does. God, who made both hands, knows all. But the left, which Augustine sees as the temporal, does not recognize the right, or spiritual (Augustine Psalms, loc. 340440, par. 5).
In verse five, Augustine takes the right hand to indicate power. Here the Lord defends us on the right side (Augustine Psalms, loc. 340140, par. 6). In verse six, the protection of God continues to shield his people on the right side.
Here Augustine seems to digress, allegorically relating God to the sun and the Church to the moon. He speaks of Arians as heretics who must face God and be "scorched by the sun" (Augustine Psalms, loc. 340153, par. 7). All doctrinal errors result in a burning judgment. However, those who are faithful before God are protected from all evil (Augustine Psalms, loc. 340170, par. 8). Even persecution will not destroy them.