What is the reward for a fasting person on a very hot day?

Fasting is a great act of worship that carries immense reward from Allah. Whoever fasts a day purely for the sake of Allah, Allah will distance his face from the Hellfire by seventy autumns. This reward includes any day a servant fasts out of faith and anticipation of reward. If the fasting occurs on an extremely hot day or involves hardship, then its reward is even greater. The Prophet, peace and blessings be upon him, said: "Indeed, your reward is commensurate with your effort and expenditure." It has been reported that Allah Almighty has decreed upon Himself that whoever thirsts himself for Allah عز وجل on a hot day, it is a right upon Allah to quench his thirst on the Day of Resurrection.