Gods, saints, and heavenly bards beheld That flight that none had paralleled, Then to the Nágas’ mother came And thus addressed the sun-bright dame: “See, Hanumán with venturous leap Would spring across the mighty deep,— A Vánar prince, the Wind-God’s seed: Come, Surasá, his course impede.

In plain words: The gods and sages watch this amazing flight. They go to Surasa, mother of the Nagas (serpent beings), and ask her to block Hanuman's way.