Mhmwd bin Khalid محمود بن خالد · The Book of Fasting

"Whoever fasts during Ramadan" and according to the Hadith of Qutaibah, the Prophet said: "Whoever spends the nights of Ramadan in prayer (Qiyam) out of faith and in the hope of reward, he will be forgiven his previous sins, and whoever spends the night of Lailat Al-Qadr in prayer out of faith and in the hope of reward, he will be forgiven his previous sins." '

"I heard Abu Saeed Al-Khudri say: 'The Messenger of Allah said: Whoever fasts one day in the cause of Allah will separate his face from the fire by (a distance of) seventy autumns."'

"Whoever fasts one day in the cause of Allah, the mighty and sublime, Allah will separate him the distance of one hundred years from the fire."