Sahih al-Bukhari 4519Book 65, Hadith 44
حَدَّثَنِي مُحَمَّدٌ، قَالَ أَخْبَرَنِي ابْنُ عُيَيْنَةَ، عَنْ عَمْرٍو، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ كَانَتْ عُكَاظٌ وَمَجَنَّةُ وَذُو الْمَجَازِ أَسْوَاقًا فِي الْجَاهِلِيَّةِ فَتَأَثَّمُوا أَنْ يَتَّجِرُوا فِي الْمَوَاسِمِ فَنَزَلَتْ {لَيْسَ عَلَيْكُمْ جُنَاحٌ أَنْ تَبْتَغُوا فَضْلاً مِنْ رَبِّكُمْ} فِي مَوَاسِمِ الْحَجِّ.
`Ukaz, Mijanna and Dhul-Majaz were markets during the Pre-islamic Period. They (i.e. Muslims) considered it a sin to trade there during the Hajj time (i.e. season), so this Verse was revealed:-- "There is no harm for you if you seek of the Bounty of your Lord during the Hajj season." (2.198)