Brahma Sutras
ॐ उपपूर्वमपीत्येके भावशमनवत्तदुक्तम् ॐ ॥ ३-४-४२॥
Some, however, consider this to be a minor sin and concede expiation as in a case of eating forbidden food. So it is explained by Jaimini.
english translation
OM upapUrvamapItyeke bhAvazamanavattaduktam OM ॥ 3-4-42॥
hk transliteration by Sanscript