Ibn Abbas recited this verse: 'It is no sin for you that you seek the bounty of your Lord', and said: The people would not trade in Mina (during the hajj), so they were commanded to trade when they proceeded from Arafat.  

قَرَأَ هَذِهِ الآيَةَ { لَيْسَ عَلَيْكُمْ جُنَاحٌ أَنْ تَبْتَغُوا فَضْلاً مِنْ رَبِّكُمْ } قَالَ كَانُوا لاَ يَتَّجِرُونَ بِمِنًى فَأُمِرُوا بِالتِّجَارَةِ إِذَا أَفَاضُوا مِنْ عَرَفَاتٍ