Maitreya said: When Lord Brahmā ordered Atri Muni to create generations after marrying Anasūyā, Atri Muni and his wife went to perform severe austerities in the valley of the mountain known as Ṛkṣa.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
मैत्रेय उवाच । ब्रह्मणा नोदितः सृष्टावत्रिर्ब्रह्मविदां वरः । सह पत्न्या ययावृक्षं कुलाद्रिं तपसि स्थितः
maitreya uvāca | brahmaṇā noditaḥ sṛṣṭāvatrirbrahmavidāṃ varaḥ | saha patnyā yayāvṛkṣaṃ kulādriṃ tapasi sthitaḥ
SB 4.1.17