Rasendracudamani 13.24

13.24

nirvāpya goghṛte samyag dvādaśābdapurātane /
śarāvasampuṭe ruddhvā ghṛtāktaṃ svedayecchanaiḥ //

having properly quenched it in cow's ghee twelve years old, / sealed it in a pair of shallow earthen dishes smeared with ghee, one should steam it gently.