Sahih Bukhari Volume 4, Book 56, Hadith 2870

حَدَّثَنَا أَحْمَدُ بْنُ يُونُسَ، حَدَّثَنَا اللَّيْثُ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ ـ رضى الله عنه أَنَّ النَّبِيَّ صلى الله عليه وسلم سَابَقَ بَيْنَ الْخَيْلِ الَّتِي لَمْ تُضَمَّرْ، وَكَانَ أَمَدُهَا مِنَ الثَّنِيَّةِ إِلَى مَسْجِدِ بَنِي زُرَيْقٍ‏.‏ وَأَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ كَانَ سَابَقَ بِهَا‏ قال ابو عبدالله:اَمَدً: غاية {فَطَالَ عَلَيهِمُ الأَمَدُ }

Narrated By Abdullah : The Prophet arranged for a horse race of the horses which had not been made lean; the area of the race was from Ath-Thaniya to the mosque of Bani Zuraiq. (The sub-narrator said, "'Abdullah bin 'Umar was amongst those who participated in that horse race.").