One verse

Srimad Bhagavatam 4.8.43

4.8.43

स्‍नात्वानुसवनं तस्मिन् कालिन्द्या: सलिले शिवे । कृत्वोचितानि निवसन्नात्मन: कल्पितासन: ॥ ४३ ॥

snatvanusavanam tasmin kalindyah salile sive krtvocitani nivasann atmanah kalpitasanah

snatva
after taking bath
anusavanam
three times
tasmin
in that
kalindyah
in the River Kalindi (the Yamuna)
salile
in the water
sive
which is very auspicious
krtva
performing
ucitani
suitable
nivasan
sitting
atmanah
of the self
kalpita-asanah
having prepared a sitting place.

Narada Muni instructed: My dear boy, in the waters of the Yamuna River, which is known as Kalindi, you should take three baths daily because the water is very auspicious, sacred and clear. After bathing, you should perform the necessary regulative principles for astanga-yoga and then sit down on your asana (sitting place) in a calm and quiet position.