PRAŚNA UPANISHAD · 1.15

तद्ये ह वै तत् प्रजापतिव्रतं चरन्ति ते मिथुनमुत्पादयन्ते ।
तेषामेवैष ब्रह्मलोको येषां तपो ब्रह्मचर्यं येषु सत्यं
प्रतिष्ठितम् ॥ १.१५॥

tadye ha vai tat prajāpativrataṃ caranti te mithunamutpādayante ।
teṣāmevaiṣa brahmaloko yeṣāṃ tapo brahmacaryaṃ yeṣu satyaṃ
pratiṣṭhitam ॥ 1.15॥

“They therefore who perform the vow of the Eternal Father produce the twin creature. But theirs is the heaven of the spirit in whom are established askesis and holiness and in whom Truth has her dwelling.

Sri Aurobindo · CWSA 18, p. 179