Shiva Purana
गवां वृषाभिभूतानां द्विजानां गुरुपूर्वकम् ॥ यस्समाचरते विप्र तमाहुर्ब्रह्मघातकम् ॥ २८॥
He who hinders cows when bulls mate with them or brahmins when they seek preceptors is called a brahmin-slayer.
english translation
gavAM vRSAbhibhUtAnAM dvijAnAM gurupUrvakam ॥ yassamAcarate vipra tamAhurbrahmaghAtakam ॥ 28॥
hk transliteration by Sanscript