Mahapadanasutta 1.28.1

1.28.1

Dhammatā esā, bhikkhave, yadā bodhisatto mātukucchimhā nikkhamati, dve udakassa dhārā antalikkhā pātubhavanti—ekā sītassa ekā uṇhassa yena bodhisattassa udakakiccaṃ karonti mātu ca.

It’s normal that, when the being intent on awakening emerges from his mother’s womb, two showers of water appear from the sky, one cool, one warm, for bathing the being intent on awakening and his mother.