Natyashastra
पूर्वरङ्गे प्रयोक्तव्यमङ्गजातमतःपरम् । एवं शुद्धो भवेच्चित्रः पूर्वरङ्गो विधानतः ॥ १५७॥
The subsidiary parts should be performed in the preliminary act. Thus, the picture becomes pure according to the rules of the preliminary act.
english translation
pUrvaraGge prayoktavyamaGgajAtamataHparam । evaM zuddho bhaveccitraH pUrvaraGgo vidhAnataH ॥ 157॥
hk transliteration by Sanscript