Mahabharata 3.82.15

शाकाहारस्य यत्सम्यग्वर्षैर्द्वादशभिः फलम्तत्फलं तस्य भवति देव्याश्छन्देन भारत

śākāhārasya yatsamyagvarṣairdvādaśabhiḥ phalamtatphalaṃ tasya bhavati devyāśchandena bhārata

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