Manusmriti

siva.sh/manusmriti/9/58

ज्येष्ठो यवीयसो भार्यां यवीयान् वाऽग्रजस्त्रियम् । पतितौ भवतो गत्वा नियुक्तावप्यनापदि ॥ ५८ ॥

sanskrit

An elder (brother) who approaches the wife of the younger, and a younger (brother who approaches) the wife of the elder, except in times of misfortune, both become outcasts, even though (they were duly) authorised.

english translation

jyeSTho yavIyaso bhAryAM yavIyAn vA'grajastriyam | patitau bhavato gatvA niyuktAvapyanApadi || 58 ||

hk transliteration by Sanscript