Abu Umamah (May Allah be pleased with him) reported:
The Prophet (ﷺ) said, "He who observes Saum (fasting) for a day in the Cause of Allah, Allah will keep his face from Hell-fire at a distance equivalent to that between heaven and the earth."[At- Tirmidhi].
App reference: Book 12, Hadith 56
Arabic/English book reference: Book 12, Hadith 1340