Mahabharata 12.192.91

अनेन धर्मप्राप्त्यर्थं शुभा दत्ता पुरानघधेनुर्विप्राय राजर्षे तपःस्वाध्यायशीलिने

anena dharmaprāptyarthaṃ śubhā dattā purānaghadhenurviprāya rājarṣe tapaḥsvādhyāyaśīline

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