أَخْبَرَنَا إِسْمَاعِيلُ بْنُ مَسْعُودٍ، قَالَ حَدَّثَنَا خَالِدٌ، قَالَ حَدَّثَنَا هِشَامٌ، قَالَ حَدَّثَنَا قَتَادَةُ، عَنْ أَنَسٍ، عَنْ زَيْدِ بْنِ ثَابِتٍ، قَالَ تَسَحَّرْنَا مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم ثُمَّ قُمْنَا إِلَى الصَّلاَةِ ‏.‏ قُلْتُ زُعِمَ أَنَّ أَنَسًا الْقَائِلُ مَا كَانَ بَيْنَ ذَلِكَ قَالَ قَدْرَ مَا يَقْرَأُ الرَّجُلُ خَمْسِينَ آيَةً ‏.‏

It was narrated that Anas said

"The Messenger of Allah and Zaid bin Thabit had Sahur, then they went and started to pray Subh." We said to Anas: "How long was there between their finishing and their starting to pray?" He said: "As long as it takes a man to recite fifty Verses."