When Does Suhur Time End?
Question

In reference to question 12602 , where you stated that stopping eating about 5 minutes before fajr (when fasting) is a form of bid'ah. I found the following hadith in Al-Bukhari: Narrated Anas: Zaid bin Thabit said "We took the sahur with the Prophet (peace and blessings of Allah be upon him). Then he stood for prayer." I asked, "What was the interval between the sahur and the adhan?" He replied "The interval was sufficient to recite fifty verses of the Quran." Chapter 13, 3:144. Reciting 50 verses should take about 5 or 10 minutes, even more. So how is it a bid'ah to stop eating 5 minutes before fajr?
Praise be to Allah.End of Suhur time
Al-Bukhari (1921) narrated from Anas that Zayd ibn Thabit said: “We ate suhur with the Prophet (peace and blessings of Allah be upon him), then he stood up to pray.” I [Anas] said: “How long was there between the adhan and suhur?” He said: “As long as it takes to recite fifty verses.”
This hadith indicates that the Prophet (peace and blessings of Allah be upon him) used to eat suhur this amount of time before the adhan, not that the Prophet (peace and blessings of Allah be upon him) started to fast and stopped eating and drinking this amount of time before Fajr. 
There is a difference between the time of suhur and the time of stopping eating and drinking . This is clear, praise be to Allah. It is like saying, “I ate suhur two hours before Fajr.” This does not mean that you started fasting from that time, rather you are simply stating what time you ate suhur at. 
What may be understood from the hadith of Zayd ibn Thabit (may Allah be pleased with him) is that it is mustahabb to delay suhur and it is not mustahabb to stop eating and drinking a while before Fajr. 
Allah has permitted those who intend to fast to eat and drink until they are certain that dawn has come. Allah says (interpretation of the meaning): 
“and eat and drink until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night), then complete your Sawm (fast) till the nightfall.” [al-Baqarah 2:187]
“So it is permissible to have intercourse, eat and drink during the nights of Ramadan from the beginning of the night until dawn comes, then we are commanded to complete the fast until night comes.” (Abu Bakr al-Jassas in Ahkam al-Quran, 1/265) 
Al-Bukhari (1919) and Muslim (1092) narrated from ‘Aishah (may Allah be pleased with her) that Bilal used to give the adhaan at night, and the Messenger of Allah (peace and blessings of Allah be upon him) said: ‘Eat and drink until Ibn Umm Maktum calls the adhan, for he does not call the adhan until the dawn comes.” 
Al-Nawawi said in al-Majmu’ (6/406): 
“Our companions and other scholars agree that suhur is Sunnah, and that delaying it is preferable. The evidence for all of that is the sahih ahadith. And because suhur and delaying suhur helps one to fast, and they involve being different to the disbelievers. Moreover the time for fasting is the day, so there is no sense in delaying iftar or refraining from eating suhur at the end of the night. 
When to stop eating and drinking in Ramadan
The Standing Committee (10/284) was asked: I read in some tafsirs that the fasting person should stop eating and drinking 20 minutes before the adhan of Fajr, and this is described as being on the safe side. How much time should there be between stopping eating and drinking and the adhan of Fajr in Ramadan? What is the ruling on one who hears the muadhdhin saying “al-salatu khayrun min al-nawm (prayer is better than sleep)” and he says that he can still drink so long as the adhan is still going on. Is this correct? 
They replied: 
The basic principle regarding when the fasting person should stop eating and drinking and should break the fast is the verse in which Allah says (interpretation of the meaning): 
“…and eat and drink until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night), then complete your Sawm (fast) till the nightfall.” [al-Baqarah 2:187]
It is permissible to eat and drink until the dawn appears, which is the white thread of light that Allah has made the latest time when it is permissible to eat and drink. When the second dawn appears, it is haram to eat and drink and do other things that break the fast. Whoever drinks whilst hearing the adhan for Fajr , if the adhan comes after the second dawn, then he has to make up that day, but if that was before dawn, then he does not have to make it up.” 
Should we stop eating and drinking 20 minutes before Fajr?
Shaykh Ibn Baz was asked about making the time for stopping eating and drinking approximately fifteen minutes before Fajr . He replied: 
“I do not know of any basis for this, rather what is indicated by the Quran and Sunnah is that we should stop eating and drinking when dawn comes, because Allah says (interpretation of the meaning): 
“…and eat and drink until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night), then complete your Sawm (fast) till the nightfall.” [al-Baqarah 2:187]
And the Prophet (peace and blessings of Allah be upon him) said: “Dawn is of two types, a dawn when it becomes haram to eat and permissible to pray, and a dawn when you should not pray [i.e., Fajr prayer] and it is permissible to eat.” (Narrated by Ibn Khuzaymah and al-Hakim, who classed it as sahih in Bulugh al-Maram)
And the Prophet (peace and blessings of Allah be upon him) said: “Bilal calls the adhan at night, so eat and drink until Ibn Umm Maktum gives the call to prayer.” The narrator said: Ibn Umm Maktum was a blind man who did not give the call to prayer until someone said to him, ‘Morning has come, morning has come.’” (Sahih – agreed upon) (Majmu’ Fatawa Ibn Baz, 15/281)
And Allah knows best.