Manusmriti

siva.sh/manusmriti/10/64

शूद्रायां ब्राह्मणाज् जातः श्रेयसा चेत् प्रजायते । अश्रेयान् श्रेयसीं जातिं गच्छत्या सप्तमाद् युगात् ॥ ६४ ॥

sanskrit

If (a female of the caste), sprung from a Brahmana and a Sudra female, bear (children) to one of the highest caste, the inferior (tribe) attains the highest caste within the seventh generation.

english translation

zUdrAyAM brAhmaNAj jAtaH zreyasA cet prajAyate | azreyAn zreyasIM jAtiM gacchatyA saptamAd yugAt || 64 ||

hk transliteration by Sanscript