Charles Ellicott Commentary Psalms 121:5

"Jehovah is thy keeper: Jehovah is thy shade upon thy right hand." — Psalms 121:5 (ASV)

Your keeper. — Notice again how the prominent word is taken up from the preceding verse and amplified, and then again repeated, and again amplified in Psalms 121:7-8, where preserve is an unfortunate substitution by the Authorised Version.

Shade. — An image of protection, and one particularly attractive to people of the East. (See Numbers 14:9, margin; Psalms 91:1; Isaiah 25:4; Isaiah 32:2.)

Upon your right hand. — Some commentators combine this expression with the figure of the shadow, supposing the psalmist, in the phrase “right hand,” to allude to the south or sunny side. But this is prosaic. No doubt there is here, as so often, a confused combination of metaphors. We have several times encountered the figure of the right-hand comrade in war, a protection to the unshielded side (Psalms 16:8; Psalms 109:31, etc.).