Psalms 121:1

(A song for ascents The simple meaning is that when the Levites began to ascend the steps, they recited this song. Although this song is not written first, there is no chronological sequence.) (In other books I found:)

A song for ascents [The Psalmist] alludes, in the second psalm, to the steps that ascend for the righteous in the future from beneath the tree of life to the Throne of Glory, as we learned in Sifrei (Ekev 47): “It does not say here, ‘A song of ascents’ but, ‘A song for ascents’; a song for the One Who is destined to make ascents for the righteous in the future.” This is what the Kalir established (in the concluding poem of the morning service for the second day of Succoth, which was composed by Rabbi Elazar the son of Rabbi Simon the son of Yochai in Chagigah, chapter “We may not expound,” see there): “And from beneath them thirty steps, one above the other until the Throne of Glory, flying and ascending with the pleasant speech of the song of ascents.”