SB 8.16.48
प्रतिपद्दिनमारभ्य यावच्छुक्लत्रयोदशीम् ।
ब्रह्मचर्यमध:स्वप्नं स्‍नानं त्रिषवणं चरेत् ॥ ४८ ॥
pratipad-dinam ārabhya
yāvac chukla-trayodaśīm
brahmacaryam adhaḥ-svapnaṁ
snānaṁ tri-ṣavaṇaṁ caret
SYNONYMS

pratipat-dinam—on the day of pratipat; ārabhya—beginning; yāvat—until; śukla—of the bright fortnight; trayodaśīm—the thirteenth day of the moon (the second day after Ekādaśī); brahmacaryam—observing complete celibacy; adhaḥ-svapnam—lying down on the floor; snānam—bathing; tri-savanam—three times (morning, evening and noon); caret—one should execute.

TRANSLATION

From pratipat until the thirteenth day of the next bright moon [śukla-trayodaśī], one should observe complete celibacy, sleep on the floor, bathe three times a day and thus execute the vow.