Manusmriti

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एवं दृढव्रतो नित्यं ब्रह्मचारी समाहितः । समाप्ते द्वादशे वर्षे ब्रह्महत्यां व्यपोहति ॥ ८१ ॥

sanskrit

He who thus (remains) always firm in his vow, chaste, and of concentrated mind, removes after the lapse of twelve years (the guilt of) slaying a Brahmana.

english translation

evaM dRDhavrato nityaM brahmacArI samAhitaH | samApte dvAdaze varSe brahmahatyAM vyapohati || 81 ||

hk transliteration by Sanscript