Anandakanda 1.7.19

1.7.19

pācayeddāhayedevaṃ secayetsaptavārakam /
evaṃ dvijātijātīyāḥ śodhitāḥ syuśca siddhidāḥ //

One should thus cook it, burn it, and sprinkle it seven times. / In this way, the [diamonds] of the twice-born classes become purified and bestow alchemical perfection.