Abdullah bin Abbas (may Allah be pleased with them both) narrates: ‘Ukaz and Dhul-Majaz were markets of the time of ignorance (which used to be held during the time of Hajj). When Allah granted dominance to Islam, people considered trading during Hajj to be a sin. The people asked the Prophet Muhammad (peace be upon him) about this, so this verse was revealed: “There is no sin upon you if you seek the bounty of your Lord.” (This means) that you do so during the time of Hajj.
Hadith Referenceصحیح ابن حبان / كتاب الحج / 3894
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - «صحيح أبي داود» (1521): خ.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط البخاري