From 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
Reference: Bukhari 1921