Matsyapurana 69.31

69.31

ekādaśyāṃ nirāhāraḥ samabhyarcya ca keśavam
rātriṃ ca sakalāṃ sthitvā snānaṃ ca payasā tathā //

Afterwards, the devotee should brush his teeth with a stick of banyan or khadîr and then rinse his mouth, facing the east or the north, and holding a kuśa in his hand. After sunset he should perform his sandhyâ and then utter: "Om namonârâyaṇâya namaḥ, twâmahaṃ śaraṇaṅgataḥ. I salute Nârâyaṇa, I throw myself under your protection." On the Ekâdaśî day, I shall keep a fast and worship Nârâyaṇa and keep a vigil at night; have a bath early in the morning (_i.e._, on the Dvâdaśî) and make an oblation of clarified butter to Fire. Puṇḍarîkâkṣa, I shall, with mind controlled, eat rice, cooked with milk, with a few good Brahmans. May that be fulfilled by Thy grace, without any obstruction.'