Mahabharata 13.110.115

एकोनत्रिंशे दिवसे यः प्राशेदेकभोजनम्सदा द्वादश मासान्वै सत्यव्रतपरायणः

ekonatriṃśe divase yaḥ prāśedekabhojanamsadā dvādaśa māsānvai satyavrataparāyaṇaḥ

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