What are "Palgei Mayim"?
Ibn Ezra: They are rivers that divide [into branches].
Who says this?
Ibn Ezra: [The author, who] laments.
Palgei Mayim: This [and also verse 49] is the Shechinah's answer, lest [Yisrael] despair 1 .
Verse 50 ("Ad Yashkif v'Yerei Hashem") implies that Hashem does not say this! Palgei Mayim must hold that verse 50 applies to what follows it - "Ad Yashkif