The Law Code of Yājñavalkya 3.1.84

3.1.84

sarpahate tv ayaṃ viśeṣaḥ | saṃvatsaraṃ yāvat purāṇoktavidhinā pañcabhyāṃ nāgapūjāṃ vidhāya pūrṇe saṃvatsare nārāyaṇabaliṃ kṛtvā sauvarṇaṃ nāgaṃ dadyāt gāṃ ca pratyakṣām | tataḥ sarvam aurdhvadehikaṃ kuryāt ||

In the case of one killed by a snake, however, there is this distinction: having performed the worship of the serpent on the fifth tithi for a full year according to the procedure stated in the Purāṇas, when the year is complete, having performed the Nārāyaṇabali, he should give a golden serpent and a living cow. Then he should perform all the post-death rites.