No, fasting on the last ten days of Hajj is not a requirement or a part of the Hajj rituals. However, fasting on the day of Arafah (the 9th day of the Islamic month of Dhu al-Hijjah) is highly recommended for those who are not performing Hajj. It is believed that this fast can expiate the sins of the previous year and the coming year. As for the pilgrims (those who are performing Hajj), it is preferred for them to abstain from fasting on the day of Arafah as it is a very strenuous day and they need to conserve all their energy to perform the Hajj rituals.