From Sahih Bukhari (Hadith 1770):
Narrated 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)
Reference: Bukhari 1770