Sahih al-Bukhari Book 9, Hadith 51
Zaid bin Thabit said, "We took the "Suhur" (the meal taken before dawn while fasting is observed)
with the Prophet (ﷺ) and then stood up for the (morning) prayer." I asked him how long the interval
between the two (Suhur and prayer) was. He replied, 'The interval between the two was just sufficient
to recite fifty to Sixth 'Ayat."
My father said, "Allah's Messenger (ﷺ) said, 'Whoever prays the two cool prayers (`Asr and Fajr) will go to Paradise.' "
Anas bin Malik said, "The Prophet (ﷺ) and Zaid bin Thabit took the 'Suhur' together and after finishing the meal, the Prophet (ﷺ) stood up and prayed (Fajr prayer)." I asked Anas, "How long was the interval between finishing their 'Suhur' and starting the prayer?" He replied, "The interval between the two was just sufficient to recite fifty 'Ayat." (Verses of the Qur'an).