Bhagavatapurana 5.24.3

5.24.3

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tan niśamyobhayatrāpi bhagavatā rakṣaṇāya prayuktaṃ sudarśanaṃ nāma bhāgavataṃ dayitam astraṃ tat tejasā durviṣahaṃ muhuḥ parivartamānam abhyavasthito muhūrtam udvijamānaś cakita-hṛdaya ārād eva nivartate tad uparāgam iti vadanti lokāḥ //

3. Observing that plight of both the Sun and the Moon the glorious Lord has appointed His Sudarsana for their protection, the most favourite weapon of the Lord, irresistible by its splendour

and constantly moving about; Rahu stands against it for a while trembling with a heart full of fear, only at a distance, and withdraws himself; this occurrence, the world calls an eclipse.