तीर्थवंशोपदेशः
Tīrtha-vaṃśa Upadeśa: Instruction on the Fruits of Sacred Waters
नान्यत्र ब्राह्मणोश्रीयात् पूर्व विप्रेण केतित: । यवीयान् पशुहिंसायां तुल्यधर्मो भवेत् स हि
nānyatra brāhmaṇośrīyāt pūrvaṁ vipreṇa ketitaḥ | yavīyān paśuhiṁsāyāṁ tulyadharmo bhavet sa hi ||
Bhīṣma said: If a Brahmin has already been invited beforehand by another Brahmin, he should not go elsewhere to eat. If he does so, he is regarded as diminished in standing, and the fault incurred is treated as comparable in gravity to the sin of animal-slaughter—because it violates the ethical duty of honoring a prior commitment and the sanctity of śrāddha hospitality.
भीष्म उवाच
One must honor a prior śrāddha invitation; breaking it by eating elsewhere is a serious breach of dharma, treated as morally weighty—likened to the sin of animal-slaughter—because it violates trust and disrupts sacred hospitality.
In Anuśāsana Parva, Bhīṣma instructs on righteous conduct and ritual-social duties. Here he lays down a rule for Brahmins regarding invitations for ritual feeding: once invited, the invitee should not accept food elsewhere, and doing so incurs grave fault.