The mature Christian is neither blind to trouble nor in fear of it, for he is following after Jesus Christ, who said, “In this world you will have trouble. But take heart! I have overcome the world” (John 16:33). Where does my help come from? As the psalmist answers, “My help comes from the LORD, the Maker of heaven and earth. He will not let your foot slip—he who watches over you will not slumber.”

3. Our protector always (vv. 7, 8). The powerful fourth stanza sums up everything that has been said in a series of intensifying statements. We have already seen that God is our guard against all evils both of the day and night, for God does not sleep at night. Now we learn that God will also 1) keep us from all harm; 2) watch over our lives; 3) watch over our comings and goings; and 4) do all of that both now and forever. 

If the first stanza asks where the help of the devout pilgrim comes from and answers that it is from the God who made heaven and earth, the next stanzas explore various ways in which that great Creator God helps his weak disciple. Stanzas two and three explore this by images, suggesting that God is like a watchman, who does not sleep, or again, like shade from the harmful effects of the sun or moon. The last stanza abandons imagery and says directly that God is our protector at all times and in all circumstances. 

Protection by God, under the watchful eye of God, is the dominant idea in the psalm. In the Hebrew text, only one word is used for what our versions translate variously as "watches over," "preserves” and “keeps.” That word (shamar) is used six times. It is found twice in the second stanza (vv. 3, 4), once in the third stanza (v. 5), and three times in stanza four (once as “keep” and twice as "watch over,” vv. 7, 8). 

Psalm 121 is the second of the pilgrim psalms, the Songs of Ascents devout Jews must have sung as they made their way to the highlands of Judah, where Jerusalem was located, for the annual feasts. When we remember that there were no real roads in those days, only well-trodden paths across the valleys, along the rivers and over mountain passes, it is easy to imagine how this psalm might have been sung by a hopeful but very weary pilgrim. He has been traveling for days. His feet are sore. His muscles ache. Jerusalem, the end of his pilgrimage, seems very distant. But then suddenly he sees the hills of Judah in the distance, and he breaks into song.