While examining the food given to him, Vasiṣṭha Muni, by his mystic power, could understand that it was unfit to eat, being the flesh of a human being. He was very angry at this and immediately cursed Saudāsa to become a man-eater.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
परिवेक्ष्यमाणं भगवान् विलोक्याभक्ष्यमञ्जसा । राजानमशपत्क्रुद्धो रक्षो ह्येवं भविष्यसि
parivekṣyamāṇaṃ bhagavān vilokyābhakṣyamañjasā | rājānamaśapatkruddho rakṣo hyevaṃ bhaviṣyasi
SB 9.9.22