Mbh 5.9.5b

And next ensued a great fight between Vritra and Indra, both fired with wrath. And there took place a terrible combat, O best of Kuru’s race. And the heroic Vritra seized the celestial lord who had performed a hundred sacrifices. And filled with wrath, he whirled Indra and threw him into his mouth. And when Indra was swallowed up by Vritra, the terrified senior gods, possessed of great might, created Jrimbhika to kill Vritra. And as Vritra yawned and his mouth opened the slayer of the Asura, Vala contracted the different parts of his body, and came out from within Vritra’s mouth. And thenceforth the yawn attaches itself to the living breath of animated beings in three worlds. And the gods rejoiced at the egress of Indra. And once again commenced the terrible fight between Vritra and Indra, both full of ire. And it was waged for a long while, O best of Bharata’s race. And when Vritra, inspired with the mighty spirit of Twashtri and himself endowed with strength, got the upper hand in fight, Indra turned back. And on his retreat, the gods became exceedingly distressed. And all of them together with Indra were overpowered by the might of Twashtri. And they all consulted with the saints, O descendant of Bharata. And they deliberated as to what was proper to be done, and were overwhelmed with dread. And seated on the top of the Mandara mountain, and bent on killing Vritra, they only bethought themselves of Vishnu, the indestructible one.’”