Srimad Bhagavatam — Dvadasha Skandha, Shloka 2
Mārkaṇḍeya Ṛṣi Tested by Indra and Blessed by Nara-Nārāyaṇa
आहुश्चिरायुषमृषिं मृकण्डतनयं जना: । य: कल्पान्ते ह्युर्वरितो येन ग्रस्तमिदं जगत् ॥ २ ॥ स वा अस्मत्कुलोत्पन्न: कल्पेऽस्मिन् भार्गवर्षभ: । नैवाधुनापि भूतानां सम्प्लव: कोऽपि जायते ॥ ३ ॥ एक एवार्णवे भ्राम्यन् ददर्श पुरुषं किल । वटपत्रपुटे तोकं शयानं त्वेकमद्भुतम् ॥ ४ ॥ एष न: संशयो भूयान् सूत कौतूहलं यत: । तं नश्छिन्धि महायोगिन् पुराणेष्वपि सम्मत: ॥ ५ ॥
āhuś cirāyuṣam ṛṣiṁ mṛkaṇḍu-tanayaṁ janāḥ yaḥ kalpānte hy urvarito yena grastam idaṁ jagat
Authorities say that Mārkaṇḍeya Ṛṣi, the son of Mṛkaṇḍu, was extraordinarily long-lived, and that at the end of the kalpa, when the universe was swallowed by the deluge of dissolution, he alone remained. Yet that same Mārkaṇḍeya—the foremost of Bhṛgu’s line—has taken birth in our own family in the present day of Brahmā, and still we have not seen any total annihilation in this kalpa. It is also renowned that, while drifting helplessly in the vast ocean of dissolution, he beheld in those dreadful waters a wondrous Person: an infant boy lying alone within the fold of a banyan leaf. O Sūta, thus our doubt and curiosity are great. O great yogī, accepted as an authority even among the Purāṇas, please cut through our confusion.
Lord Brahmā’s day, consisting of his 12 hours, lasts 4 billion 320 million years, and his night is of the same duration. Apparently Mārkaṇḍeya lived throughout one such day and night and in the following day of Brahmā continued living as the same Mārkaṇḍeya. It seems that when annihilation occurred during Brahmā’s night, the sage wandered throughout the fearful waters of destruction and saw within those waters an extraordinary personality lying on a banyan leaf. All of these mysteries concerning Mārkaṇḍeya will be clarified by Sūta Gosvāmī at the request of the great sages.