Rasarnava 2.93

2.93

anāhate brahmarandhre manaḥ kṛtvā nirāmaye
karanyāsaṃ purā kṛtvā aṅganyāsamanantaram
yathāśakti japenmantraṃ rasendrasya samāhitaḥ //

Having placed the mind in the anāhata [chakra] and in the faultless brahmarandhra, / having first performed the ritual placement on the hands and then the ritual placement on the limbs, / one should, collected in mind, recite the mantra of the lord of mercury according to one's capacity.