Revākhaṇḍa ascribed to the Vāyupurāṇa (RKV) 102.10

102.10

godānaṃ pāṇḍavaśreṣṭha trayodaśyāṃ prakārayet /
caitre māsi site pakṣe tatra gatvā jitendriyaḥ //

One should make the gift of a cow on the thirteenth lunar day, O best of Pāṇḍavas,
having gone there with senses controlled during the bright fortnight of the month of Caitra.