Sahih Bukhari Volume 5, Book 64, Hadith 4258

حَدَّثَنَا سُلَيْمَانُ بْنُ حَرْبٍ، حَدَّثَنَا حَمَّادٌ ـ هُوَ ابْنُ زَيْدٍ ـ عَنْ أَيُّوبَ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ قَدِمَ رَسُولُ اللَّهِ صلى الله عليه وسلم وَأَصْحَابُهُ فَقَالَ الْمُشْرِكُونَ إِنَّهُ يَقْدَمُ عَلَيْكُمْ وَفْدٌ وَهَنَهُمْ حُمَّى يَثْرِبَ‏.‏ وَأَمَرَهُمُ النَّبِيُّ صلى الله عليه وسلم أَنْ يَرْمُلُوا الأَشْوَاطَ الثَّلاَثَةَ، وَأَنْ يَمْشُوا مَا بَيْنَ الرُّكْنَيْنِ، وَلَمْ يَمْنَعْهُ أَنْ يَأْمُرَهُمْ أَنْ يَرْمُلُوا الأَشْوَاطَ كُلَّهَا إِلاَّ الإِبْقَاءُ عَلَيْهِمْ‏

Narrated By Ibn Abbas : When Allah's Apostle and his companions arrived (at Mecca), the pagans said, "There have come to you a group of people who have been weakened by the fever of Yathrib (i.e. Medina)." So the Prophet ordered his companions to do Ramal (i.e. fast walking) in the first three rounds of Tawaf around the Ka'ba and to walk in between the two corners (i.e. the black stone and the Yemenite corner). The only cause which prevented the Prophet from ordering them to do Ramal in all the rounds of Tawaf, was that he pitied them.