Charak Samhita
न सतो न गुरून् परिवदेत्, नाशुचिरभिचारकर्मचैत्यपूज्यपूजाध्ययनमभिनिर्वर्तयेत् ॥२३॥
॥ Behavioural code with preceptors॥ -One should not speak ill of noble persons and preceptors. -One should not perform spells, worship of sacred trees and superiors, and studies while remaining impure.
english translation
na sato na gurUn parivadet, nAzucirabhicArakarmacaityapUjyapUjAdhyayanamabhinirvartayet ॥23॥
hk transliteration by Sanscript