Shiva Purana
पद्भ्यां शूद्रस्समुत्पन्न इति तस्य मुखाच्छ्रुतिः ॥ किमु स्थितिमधःस्थानादाप्नुवन्ति ह्यतो वद ॥ २ ॥
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