Taittirīyopaniṣat 01.07

अथाधि प्रजम् । माता पूर्वरूपम्। पितोत्तररूपम्। प्रजा सन्धिः। प्रजननं सन्धानम्। इत्यधि प्रजम् ॥७॥

athādhi prajam । mātā pūrvarūpam। pitottararūpam। prajā sandhiḥ। prajananaṃ sandhānam। ityadhi prajam ॥7॥

[अथ (atha) - now; अधि (adhi) - concerning; प्रजम् (prajam) - offspring; माता (mātā) - mother; पूर्वरूपम् (pūrvarūpam) - former form; पिता (pitā) - father; उत्तररूपम् (uttararūpam) - latter form; प्रजा (prajā) - offspring; सन्धिः (sandhiḥ) - union; प्रजननम् (prajananam) - procreation; सन्धानम् (sandhānam) - joining; इति (iti) - thus; अधि (adhi) - concerning / bringing together; प्रजम् (prajam) - offspring;]

Now, regarding offspring: the mother is the prior form, the father is the subsequent form; the offspring is the union, and procreation brings them together. Thus is the teaching concerning offspring.