From Anas ibn Maalik from Zayd ibn Thaabit radi Allaahu ‘anhumaa who said:
We took the suhoor with the Messenger of Allaah sall Allaahu ‘alaihi wa sallam, then he stood up for the prayer.
Anas said: “I said to Zayd, “How long was it between the adhaan (meaning the iqaamah) and the suhoor?”
He said, “The time taken (to recite) fifty aayaat.”
The Shaykh Muhammad ibn Saalih al ‘Uthaymeen rahimahullaah commented:
Since from the goals behind taking suhoor is to strengthen the body upon fasting and preserving its energy, then it is from wisdom to delay it.
And it is that Anas ibn Maalik related from Zayd ibn Thaabit radi Allaahu ‘anhumaa that he took the suhoor in the company of the Prophet sall Allaahu ‘alaihi wa sallam in his house, then he stood up for the prayer, and there was not between the prayer and his finishing the suhoor but the length of time taken for the reciter to recite fifty medium length aayaat from the Qur-aan with a recitation that was neither rapid nor slow
(taken from Sh Uthaymeen’s explanation of ‘Umdat-ul-Ahkaam
translated by Nasser ibn Najam)