Śrīmad-Bhāgavatam · Text 12.13.2
Who is speaking and story frame
पृष्ठे भ्राम्यदमन्दमन्दरगिरिग्रावाग्रकण्डूयना-
न्निद्रालो: कमठाकृतेर्भगवत: श्वासानिला: पान्तु व: ।
यत्संस्कारकलानुवर्तनवशाद् वेलानिभेनाम्भसां
यातायातमतन्द्रितं जलनिधेर्नाद्यापि विश्राम्यति ॥ २ ॥
pṛṣṭhe bhrāmyad amanda-mandara-giri-grāvāgra-kaṇḍūyanān
nidrāloḥ kamaṭhākṛter bhagavataḥ śvāsānilāḥ pāntu vaḥ
yat-saṁskāra-kalānuvartana-vaśād velā-nibhenāmbhasāṁ
yātāyātam atandritaṁ jala-nidher nādyāpi viśrāmyati
When the Supreme Personality of Godhead appeared as Lord Kūrma, a tortoise, His back was scratched by the sharp-edged stones lying on massive, whirling Mount Mandara, and this scratching made the Lord sleepy. May you all be protected by the winds caused by the Lord’s breathing in this sleepy condition. Ever since that time, even up to the present day, the ocean tides have imitated the Lord’s inhalation and exhalation by piously coming in and going out.
Read the purport on Vedabase.ioFrom Canto 10, chapter 14 onward, the translation and purports were completed by Śrīla Prabhupāda's disciples after his departure, and published by the Bhaktivedanta Book Trust.