Volume 6, Book 60, Number 37:
Narrated ‘Adi bin Hatim:
I said, “O Allah’s Apostle! What is the meaning of the white thread distinct from the black thread?
Are these two threads?” He said, “You are not intelligent if you watch the two threads.” He then ad –
ded, “No, it is the darkness of the night and the whiteness of the day.”