Manusmriti
उत्सादनं च गात्राणां स्नापनौच्छिष्टभोजने । न कुर्याद् गुरुपुत्रस्य पादयोश्चावनेजनम् ॥ २०९ ॥
(A student) must not shampoo the limbs of his teacher’s son, nor assist him in bathing, nor eat the fragments of his food, nor wash his feet.
english translation
utsAdanaM ca gAtrANAM snApanaucchiSTabhojane । na kuryAd guruputrasya pAdayozcAvanejanam ॥ 209 ॥
hk transliteration by Sanscript