Psalms 121 - Dummelow's Commentary on the Bible

Hills] RV 'mountains.' The mountains suggest strength, and the Psalmist asks a question, 'Whence shall my help come?' The answer is given in Psalms 121:2 : 'from Him who made the mountains and all else.' If this Ps. were sung going up to Jerusalem then the 'mountains' may be the hills around Jerusalem, or those on which that city is built.

The song of the traveller, whose guide is Jehovah.

Shade] i.e. shelter for defence.

A belief in the injurious influence of the moon is an almost universal superstition. If e.g. the moon shines on the face of a sleeper he may become blind: cp. 'moonstruck.'