he asked the Messenger of Allah about the verse "Until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night)." He said: "It is the blackness of the night and the whiteness of the day." '
Sunan an-Nasa'i Book 22, Hadith 80
← Previous Hadith if one of them went to sleep before eating supper, it was not permissible for him to eat or drink anything that night or the following day, until the sun had set. (That continued) until this Verse was revealed: "And eat and drink until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night)." He said: "This was revealed concerning Abu Qais bin 'Amr who came to his family after Maghrib when he was fasting, and said: 'Is there anything to eat?" His wife said: 'No , but I will go out, and he lay down and slept. She came back and found him sleeping, so she woke him up, but he did not eat anything. He spent the night fasting and woke up the next day fasting, until he passed out at midday. That was before this Verse was revealed, and Allah revealed it concerning him." '

Sunan an-Nasa'i Book 22, Hadith 79 Next Hadith → "Bilal calls the Adhan at night to awaken those of you who are asleep, and so that those who are praying Qiyam cam return. Dawn is not when the light appears like this" - and he gestured with his hand - "rather dawn is when it appears like this: - and he gestured with his two forefingers. '

Sunan an-Nasa'i Book 22, Hadith 81