Arthashastra
वट कषाय स्नातः सह चर कल्क दिग्धः कृष्णो भवति ॥
Whoever bathes in the decoction of vata (banyan tree) and rubs his body with the paste prepared from sahachara (yellow barleria) becomes black.
english translation
vaTa kaSAya snAtaH saha cara kalka digdhaH kRSNo bhavati ॥
hk transliteration by Sanscript