Holy is He Who created all things in pairs, of what the earth grows, and of themselves, and of what they know not.
Islam, the Holy Qur’an, 36:37
Faith and unbelief cannot be combined together in the heart of a man, nor can dishonesty and truthfulness be combined together, nor can treachery and trustworthiness be combined together.
Islam, the Holy Prophet (sa), Hadith of Musnad Ahmad
Be it known that man is drawn by two forces, the force of good and the force of evil. The Islamic Shariah attributes the first to Angels, and the second to Satan. This means that there are two forces acting upon man, and he at times leans towards good, and at times inclines towards evil.
Islam, the Promised Messiah (as), Lecture Lahore, p. 41
Observe how all God’s creations borrow from each other: day borrows from night and night from day, but they do not go to law one with another as mortals do…The moon borrows from the stars and the stars from the moon…the sky borrows from the earth and the earth from the sky…All of God’s creatures borrow from the other, yet make peace with one another without lawsuits; but if man borrows from his friend, he seeks to swallow him up with usury and robbery.
Judaism, Midrash, Exodus Rabbah 31.15
All things are twofold, one opposite the other, and he has made nothing incomplete. One confirms the good things of the other, and who can have enough of beholding his glory?
Christianity, Sirach 42.24-25
All life, all pulsation in creation throbs with the mighty declaration of the biune truth of Shiva-Shakti, the eternal He and the eternal She at play in manifestation.
Hinduism, Kularnava Tantra 3
Therefore the Innate is twofold, for wisdom is the woman and means is the man. Thereafter these both become twofold, distinguished as absolute and relative. In man there is this twofold nature: the thought of enlightenment [relative] and the bliss arising from it [absolute]; in woman too it is the same, the thought of enlightenment and the bliss arising from it.
Buddhism, Hevajra Tantra 8.29
The Great Primal Beginning (t’ai chi) generates the two primary forces [yang and yin]. The two primary forces generate…the great field of action.