"Hail, O Source of Every Blessing"

Years ago, I noticed a small feature in "Hail, O Source of Every Blessing."  I neglected to write about it at the time, but I ran across it again recently.

About halfway through the first verse, there's the line "Grateful now, we fall before You," sung to this musical phrase from the tune "O Durchbrecher":

The melody descends, musically illustrating this "fall[ing]."