Garudapurana 1.123.1

1.123.1

śrīgaruḍamahāpurāṇam- 123
brahmovāca /
vratāni kārtike vakṣye snātvā viṣṇuṃ prapūjayet /
ekabhaktena naktena māsaṃ vāyācitena vā //

The Glorious Garuḍa Mahāpurāṇa — 123
Brahmā said:
I shall speak of the religious observances in the month of Kārtika: having bathed, one should worship Viṣṇu,
for a month by eating a single meal, by eating only at night, or by eating only unbegged food,