Śrīmad-Bhāgavatam · Text 10.87.9
Who is speaking and story frame
श्रीभगवानुवाच
स्वायम्भुव ब्रह्मसत्रं जनलोकेऽभवत् पुरा ।
तत्रस्थानां मानसानां मुनीनामूर्ध्वरेतसाम् ॥ ९ ॥
śrī-bhagavān uvāca
svāyambhuva brahma-satraṁ
jana-loke ’bhavat purā
tatra-sthānāṁ mānasānāṁ
munīnām ūrdhva-retasām
The Personality of Godhead said: O son of self-born Brahmā, once long ago on Janaloka, wise sages who resided there performed a great sacrifice to the Absolute Truth by vibrating transcendental sounds. These sages, mental sons of Brahmā, were all perfect celibates.
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.