Sherayah will through the Sefer in the Pras when he is in Bavel. Pras is a border of Eretz Yisrael!
Radak: I heard that the river extends until Bavel 1 .
One may infer so from Shabbos 65b. It says that [in Bavel,] the Pras (when its water increases) is a witness of rain in Eretz Yisrael! (PF)