Shiva Purana

siva.sh/siva-purana/rudra-samhita/143/46

मुखबाहूरुसञ्जातं चातुर्वर्ण्य सहोदितम् ।। कल्पनेयं कृता पूर्वैर्न घटेत विचारतः ।। ४६ ।।

sanskrit

Some of the ancestors thought that the four castes are born of mouth, arms, thighs etc. of Brahmā.But when we consider, this does not fit in properly.

english translation

mukhabAhUrusaJjAtaM cAturvarNya sahoditam || kalpaneyaM kRtA pUrvairna ghaTeta vicArataH || 46 ||

hk transliteration by Sanscript