Śrīmad-Bhāgavatam · Text 10.3.36
Who is speaking and story frame
एवं वां तप्यतोस्तीव्रं तप: परमदुष्करम् ।
दिव्यवर्षसहस्राणि द्वादशेयुर्मदात्मनो: ॥ ३६ ॥
evaṁ vāṁ tapyatos tīvraṁ
tapaḥ parama-duṣkaram
divya-varṣa-sahasrāṇi
dvādaśeyur mad-ātmanoḥ
Thus you spent twelve thousand celestial years performing difficult activities of tapasya in consciousness of Me [Kṛṣṇa consciousness].
Read this verse on Vedabase.ioThis verse has no purport; its meaning is explained by the verses around it.