Dear Patrick, This is almost exactly as it is found at Mbh 18.49:
maharṣir bhagavān vyāsaḥ kṛtvemāṃ saṃhitāṃ purāślokaiś caturbhir bhagavān putram adhyāpayac chukamśraddhayā parayā bhaktyā śrāvyate cāpi yena tuya imāṃ saṃhitāṃ puṇyāṃ putram adhyāpayac chukammātāpitṛsahasrāṇi putradāraśatāni casaṃsāreṣv anubhūtāni yānti yāsyanti cāpareharṣasthānasahasrāṇi bhayasthānaśatāni cadivase divase mūḍham āviśanti na paṇḍitamūrdhvabāhur viraumy eṣa na ca kaścic chṛṇoti me
dharmād arthaś ca kāmaś ca sa kimarthaṃ na sevyate (18.5.46-49)