अग्निनिचयः (Agninichaya) / The Accumulation of Sacred Fire & the Classification of Pitṛs by Time-Order
वेलां च नियतिं चैव तृतीयां चायतिं विदुः / धातुश्चैवायतिः पत्नी विधातुर्नियतिः स्मृता
velāṃ ca niyatiṃ caiva tṛtīyāṃ cāyatiṃ viduḥ / dhātuścaivāyatiḥ patnī vidhāturniyatiḥ smṛtā
They are known as Velā, Niyati, and thirdly Ayati. Ayati is said to be the wife of Dhātu, and Niyati is remembered as the wife of Vidhātu.