Manusmriti

siva.sh/manusmriti/3/178

यावतः संस्पृशेदङ्गैर्ब्राह्मणान् शूद्रयाजकः । तावतां न भवेद् दातुः फलं दानस्य पौर्तिकम् ॥ १७८ ॥

sanskrit

The giver (of a Sraddha) loses the reward, due for such a non-sacrificial gift, for as many Brahmanas as a (guest) who sacrifices for Sudras may touch (during the meal) with his limbs.

english translation

yAvataH saMspRzedaGgairbrAhmaNAn zUdrayAjakaH | tAvatAM na bhaved dAtuH phalaM dAnasya paurtikam || 178 ||

hk transliteration by Sanscript