Fasting is a quarter of Faith according to the following two prophetic news (hadith): “Fasting is half of constancy,” and “Constancy is half of Faith.”

God said: "They slept little at night, and in the last hours of the night they implored forgiveness [from God]."

The Prophet (SWS) said: "Whoever keeps vigil (in devotions) during the nights of Ramadan with faith and sincerity will have his past sins forgiven." Narrated by Al-Bukhari (2008) and Muslim (759).