 The verse in the Qur'an in Surah Baqarah ayah number 187, which Allah Subhanahu Wa Ta-A'la says, So eat and drink until it becomes clear to you the difference between the white thread and the black thread. So there was a companion named Aideed Nuhattin, who kept a white thread and a black thread under his pillow, and he kept looking at them while all the lights were out in his house. And the minute he's able to distinguish between the two, he would stop eating and begin fasting. So that's how he interpreted the verse, because that's what it says. Khaytu al-Abyat, khaytu al-Aswadah, literally what it says. White thread, black thread, right? So he consulted the Prophet sallallahu alayhi sallam, and the Prophet sallallahu alayhi sallam said, no, that's not what the verse means. You don't have to look at two pieces of thread. He says that the thread is the darkness of the night or the whiteness of the day. So it's important to go to the sunnah in order to understand what the Qur'an is saying.