Sayyiduna ‘Adi bin Hatim (may Allah be pleased with him) narrates: When this verse was revealed: "Until the white thread becomes distinct to you from the black thread," I took a white thread and a black thread and placed them under my pillow. I kept observing them, but they did not become distinct to me. I mentioned this to the Prophet (peace and blessings be upon him), and he laughed. He said: "Your pillow is very wide; what is meant is the night."