Is throwing on the thirteenth of Dhul-Hijjah optional and not obligatory, and is it permissible to depart after throwing on the twelfth day without remaining in Mina for all the days of Tashreeq?

It is permissible for a pilgrim to hasten on the second day of the days of stoning, which are the eleventh and twelfth of Dhul-Hijjah, and to depart from Mina before sunset, due to the Almighty's saying: "But whoever hastens off in two days—there is no sin upon him; and whoever delays—there is no sin upon him for he who fears Allah." However, if the sun sets on the twelfth day while he is still in Mina, he must stay the night of the thirteenth and stone the three Jamarat after zawal (midday). Hastening is permissible, but delaying is better and brings greater reward, as the Prophet, peace and blessings be upon him, did it.