When this verse was revealed." Eat and drink till the white streak becomes distinct from the dark streak for you," the person who decided to observe fast tied on one of his feet a black thread and on the other a white thread. And he went on eating and drinking till he could distinguish (between their colour) on seeing them. It was after this that Allah reveal- ed (the words): min al-fajr. And they (the Muslims) came to know that (the word khait) refers to the night and day.
Bilal would pronounce Adhan (at the fag end of the night in order to inform the people about the time of the Sahri). So you eat and drink till you hear the Adhan of Ibn Umm Maktum (which was pro- nounced at the conclusion of the Sahri and the commencement of the fast).
Bilal announces Adhan at (the fag end of the) night (i. e. Sahri), so eat and drink till the son of Umm Maktum announces Adhan. And he (the narrator) said: And the (difference of time) between their (Adhans) was not more than this that one climbed down (from the minaret) and the other climbed up (to announce Adhan).
وَحَدَّثَنَا ابْنُ نُمَيْرٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا عُبَيْدُ اللَّهِ، حَدَّثَنَا الْقَاسِمُ، عَنْ عَائِشَةَ، - رضى الله عنها - عَنِ النَّبِيِّ صلى الله عليه وسلم بِمِثْلِهِ .
A hadith like this has been transmitted on the authority of 'A'isha (Allah be pleased with her).
The dawn is not like it as it is said; he then gathered his fingers and lowered them. But he said, it is like this (and he placed the index finger upon the other one and spread his hand).
This hadith has been narrated on the authority of Sulaiman Taimi with the same chain of transmitters and, at the end, it was said that the first Adhan was meant to awaken those who were in slumber amongst them and in order to make them turn who stand in (prayer) among them (towards food at the commencement of the fast). Jarir (one of the narrators) said that the Messenger (ﷺ) did not say like this but he said like it (true dawn) that the streaks of (true dawn ) are horizontal and not vertical.
حَدَّثَنَا شَيْبَانُ بْنُ فَرُّوخَ، حَدَّثَنَا عَبْدُ الْوَارِثِ، عَنْ عَبْدِ اللَّهِ بْنِ سَوَادَةَ الْقُشَيْرِيِّ، حَدَّثَنِي وَالِدِي، أَنَّهُ سَمِعَ سَمُرَةَ بْنَ جُنْدُبٍ، يَقُولُ سَمِعْتُ مُحَمَّدًا، صلى الله عليه وسلم يَقُولُ
Samura b. Jandub reported Muhammad (ﷺ) as saying. The call of Bilal may not mislead any one of you (and he may, under the wrong impression gathered from it, refrain) from taking meal before the commencement of the fast (for the streaks) of this whiteness (which are vertical indicate the false dawn and the true dawn with which the fast commences is that when the streaks of light are) spread.