Shiva Purana
अलब्धलाभ एवैष कोटिकोटिगुणाधिकः ॥ तस्मान्मे मुखतो लब्धं वर्णधर्मं समाचरेत् ॥ २६ ॥
This is millions of times more than the unrealized gain. Therefore one should practice the religious duties of the varṇas as received from My mouth.
english translation
alabdhalAbha evaiSa koTikoTiguNAdhikaH ॥ tasmAnme mukhato labdhaM varNadharmaM samAcaret ॥ 26 ॥
hk transliteration by Sanscript