Atharvaveda 5.1.1

5.1.1

ŕ̥dhaṅmantro yóniṃ yá ābabhū́vāmŕ̥tāsur várdhamānaḥ sujánmā |
ádabdhāsur bhrā́jamānó 'heva tritó dhartā́ dādhāra trī́ṇi ||1||

He who came to (ā-bhū) the womb (yóni) with a special sacred text (? ṛ́dhan̄mantra), of immortal spirit (-ásu), increasing, of good birth, of unharmed spirit, shining like the days—Trita the maintainer maintained three (trí, neuter).