Varahashrautasutra 3.2.2.42

3.2.2.42

chandogānāṃ jagatyaḥ prātaḥsavanaṃ bhajante gāyatryo mādhyandinaṃ triṣṭubhastṛtīyasavanam chandobhiravyūhenānuṣṭubhaḥ prātaḥsavanaṃ bhajante jagatyo mādhyandinaṃ gāyatryastṛtīyasavanam

The jagatī verses of the Sāmaveda chanters belong to the morning pressing, the gāyatrī verses to the midday pressing, the triṣṭubh verses to the third pressing; with the non-shifting of the metres, the anuṣṭubh verses belong to the morning pressing, the jagatī verses to the midday pressing, and the gāyatrī verses to the third pressing.