Vikukṣi offered the remnants of the flesh to King Ikṣvāku, who gave it to Vasiṣṭha for purification. But Vasiṣṭha could immediately understand that part of the flesh had already been taken by Vikukṣi, and therefore he said that it was unfit to be used in the śrāddha ceremony.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
शेषं निवेदयामास पित्रे तेन च तद्गुरुः । चोदितः प्रोक्षणायाह दुष्टमेतदकर्मकम्
śeṣaṃ nivedayāmāsa pitre tena ca tadguruḥ | coditaḥ prokṣaṇāyāha duṣṭametadakarmakam
SB 9.6.8