Valmiki Ramayana 7.60.15

तस्य तद्वचनं श्रुत्वा साधुकारो महानभूत् ।ऋषीणामुग्रतपसां यमुनातीरवासिनाम्॥

tasya tadvacanaṃ śrutvā sādhukāro mahānabhūt |ṛṣīṇāmugratapasāṃ yamunātīravāsinām ||

Our plain-language meaning of this verse is waiting for scholar review.