The people used to trade, in the beginning, at Mina, Arafat, the market place of Dhul-Majaz, and during the season of hajj. But (later on) they became afraid of trading while they were putting on ihram. So Allah, glory be to Him, sent down this verse: "It is no sin for you that you seek the bounty of your Lord during the seasons of hajj." Ubayd ibn Umayr told me that he (Ibn Abbas) used to recite this verse in his codex.
أَنَّ النَّاسَ فِي أَوَّلِ الْحَجِّ كَانُوا يَتَبَايَعُونَ بِمِنًى وَعَرَفَةَ وَسُوقِ ذِي الْمَجَازِ وَمَوَاسِمِ الْحَجِّ فَخَافُوا الْبَيْعَ وَهُمْ حُرُمٌ فَأَنْزَلَ اللَّهُ سُبْحَانَهُ { لَيْسَ عَلَيْكُمْ جُنَاحٌ أَنْ تَبْتَغُوا فَضْلاً مِنْ رَبِّكُمْ } فِي مَوَاسِمِ الْحَجِّ قَالَ فَحَدَّثَنِي عُبَيْدُ بْنُ عُمَيْرٍ أَنَّهُ كَانَ يَقْرَأُهَا فِي الْمُصْحَفِ