That the Prophet (ﷺ) said: "A worshipper does not fast a day in the cause of Allah except that, that day (of fasting) distances the Fire from his face by seventy autumns."

This Hadith is Hasan Sahih.
Jami` at-Tirmidhi Book 22, Hadith 5
← Previous Hadith From 'Urwah , and Sulaiman bin Yasar, that they reported to him from Abu Hurairah that the Prophet (ﷺ) said: "Whoever fasts a day in the cause of Allah, Allah shall distance him from the Fire by seventy autumns." One of them said "seventy" and the other said: "forty".

This Hadith is a Gharib Hadith from this route. Abu Al-Aswad's name is Muhammad bin 'Abdur-Rahman bin Nawfal Al-Asadi Al-Madani.

There are narrations on this topic from Abu Sa'eed, Anas, 'Uqbah bin 'Amir, and Abu Umamah

Jami` at-Tirmidhi Book 22, Hadith 4 Next Hadith → That the Prophet (ﷺ) said, "Whoever fasts a day in the cause of Allah, Allah shall put between him and the Fire a trench whose distance is like that between the heavens and the earth."

This Hadith is Gharib as a narration of Abu Umamah.

Jami` at-Tirmidhi Book 22, Hadith 6