It is narrated from Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Fasting and the Qur'an will intercede for the servant on the Day of Resurrection. Fasting will say: My Lord, I kept him from food and drink during the day, so accept my intercession for him. And the Qur'an will say: My Lord, I kept him from sleep at night, so accept my intercession for him. So the intercession of both will be accepted."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13685