निगीर्णो ऽप्यसुरेन्द्रेण न ममारोदरं गतः ।
महापुरुषसन्नद्धो योगमायाबलेन च ॥ ३१ ॥
nigirnah-swallowed; api-although; asura-indrena-by the best of the demons, Vrtrasura; na-not; mamara-died; udaram-the abdomen; gatah-reaching; maha-purusa-by the armor of the Supreme Lord, Narayana; sannaddhah-being protected; yoga-maya-balena-by the mystic power that Indra himself possessed; ca-also.
The protective armor of Narayana, which Indra possessed, was identical with Narayana Himself, the Supreme Personality of Godhead. Protected by that armor and by his own mystic power, King Indra, although swallowed by Vrtrasura, did not die within the demon's belly.