Volume 1, Book 10, Number 550:
Narrated Qatada:
Anas bin Malik said, “The Prophet and Zaid bin Thabit took the ‘Suhur’ together and after finishing
the meal, the Prophet 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 Quran).”