Hiranyakeshigrihyasutra 1.1.2.13

1.1.2.13

uttaraṃ paridhisaṃdhimanvavahṛtya darvīm \ prajāpataye manave svāhā \ iti manasā dhyāyandakṣiṇāprāñcamṛjuṃ dīrghaṃ saṃtataṃ juhoti \13\

Approaching the Darvi (to the fire) by the northerly junction of the pegs (laid round the fire), and fixing his mind on (the formula), 'To Pragâpati, to Manu svâhâ!' (without pronouncing that Mantra), he sacrifices a straight, long, uninterrupted (stream of Âgya), directed towards the south-east.