Agniveshyagrihyasutra 1.2.1.7

1.2.1.7

kāṇḍanāmāni vā sāvitrīmṛgvedaṃ yajurvedaṃ sāmavedam atharvavedaṃ sadasaspatimiti hutvā tryahamekāhaṃ vā kṣamya yathādhyāyamadhyetavyamiti vadanti \

Or, having offered to the names of the sections, to the Sāvitrī, the Ṛgveda, the Yajurveda, the Sāmaveda, the Atharvaveda, and the Lord of the Assembly, they say that, after waiting for three days or one day, one should study according to the [traditional] study.