The Law Code of Yājñavalkya 1.5.78

1.5.78

iti varṇayanti | nama ity anye | tatra vaiśvadevaṃ laukike 'gnau kartavyaṃ na vaivāhike 'gnāv ity ācāryāḥ || 1.121 ||

Others say [it is merely] the word "Namaḥ". There, the teachers state that the vaiśvadeva rite is to be performed in the secular fire, not in the nuptial fire. || 1.121