Śatapatha Brāhmaṇa ("of a hundred paths") 3.1.4.17

3.1.4.17

atha yaddhruvāyāmājyam pariśiṣṭam bhavati | tajjuhvāmānayati triḥ sruveṇājyavilāpanyā adhi juhvāṃ gṛhṇāti yattṛtīyaṃ gṛhṇāti tatsruvamabhipūrayati

In the first place he pours the butter, which remains in the dhruvâ, into the guhû. He then ladles with the sruva three times butter from the melting-pot into the guhû: with what he takes the third time he fills the sruva.