Shiva Purana

siva.sh/siva-purana/uma-samhita/21/2

पद्भ्यां शूद्रस्समुत्पन्न इति तस्य मुखाच्छ्रुतिः ।। किमु स्थितिमधःस्थानादाप्नुवन्ति ह्यतो वद ।। २ ।।

sanskrit

It is said from his mouth that a śūdra was born from his feet What position do they attain from the lower positions, therefore tell me.

english translation

padbhyAM zUdrassamutpanna iti tasya mukhAcchrutiH || kimu sthitimadhaHsthAnAdApnuvanti hyato vada || 2 ||

hk transliteration by Sanscript