Sahih al-Bukhari 4413
Sahih al-Bukhari · Book 64: Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi) · Hajjat-ul-Wada
Narrated Hisham's father:
حَدَّثَنَا مُسَدَّدٌ ، حَدَّثَنَا يَحْيَى ، عَنْ هِشَامٍ ، قَالَ حَدَّثَنِي أَبِي قَالَ، سُئِلَ أُسَامَةُ وَأَنَا شَاهِدٌ، عَنْ سَيْرِ النَّبِيِّ، صلى الله عليه وسلم فِي حَجَّتِهِ. فَقَالَ الْعَنَقَ، فَإِذَا وَجَدَ فَجْوَةً نَصَّ.
In my presence, Usama was asked about the speed of the Prophet (ﷺ) during his Hajj. He replied, "It was Al-`Anaq (i.e. moderate easy speed) and if he encountered an open space, he used to increase his speed."