Sahih Bukhari
Hadith #1921
Narrated Anas:Zaid bin Thabit said, ""We took the Suhur with the Prophet (ﷺ) . Then he stood for the prayer."" I asked, ""What was the interval between the Suhur and the Adhan?"" He replied, ""The interval was sufficient to recite fifty verses of the Qur'an