Sahih Bukhari Volume 2, Book 25, Hadith 1771

حَدَّثَنَا عُثْمَانُ بْنُ الْهَيْثَمِ، أَخْبَرَنَا ابْنُ جُرَيْجٍ، قَالَ عَمْرُو بْنُ دِينَارٍ قَالَ ابْنُ عَبَّاسٍ ـ رضى الله عنهما ـ كَانَ ذُو الْمَجَازِ وَعُكَاظٌ مَتْجَرَ النَّاسِ فِي الْجَاهِلِيَّةِ، فَلَمَّا جَاءَ الإِسْلاَمُ كَأَنَّهُمْ كَرِهُوا ذَلِكَ حَتَّى نَزَلَتْ ‏{‏لَيْسَ عَلَيْكُمْ جُنَاحٌ أَنْ تَبْتَغُوا فَضْلاً مِنْ رَبِّكُمْ‏}‏ فِي مَوَاسِمِ الْحَجِّ

Narrated By Ibn 'Abbas : Dhul-Majaz and 'Ukaz were the markets of the people during the Pre-Islamic period of ignorance. When the people embraced Islam, they disliked to do bargaining there till the following Holy Verses were revealed: There is no harm for you If you seek of the bounty Of your Lord (during Hajj by trading, etc.) (2.198)