Psalms 121:1-8: in context

Psalm 121 is one of the Songs of Ascents, sung by pilgrims walking up to Jerusalem for the festivals. Knowing that changes the first line. I lift up my eyes to the hills, from where does my help come? The hills are the terrain he is about to cross, and they were dangerous, full of the shrines of other gods and the practical hazards of the road.

The answer refuses the hills entirely: my help comes from the LORD, who made heaven and earth. Then the psalm changes voice, from I to you, as if someone else is now speaking over the traveler. He will not let your foot be moved, he who keeps you will not slumber. Behold, he who keeps Israel will neither slumber nor sleep.

The word keep runs six times through eight verses. The LORD is your keeper, your shade on your right hand, keeping you from all evil, keeping your life, keeping your going out and your coming in from this time forth and forevermore. Sun by day, moon by night, the two dangers of a journey. It is a travel blessing, spoken to someone who is leaving, and it does not promise an easy road. It promises a keeper who does not fall asleep on watch. Who is about to set out that I could say something like this to, before they go?