It is narrated from Sayyiduna Jundub bin Abdullah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever prays the Fajr prayer comes under the protection (care) of Allah. So see to it that Allah does not demand from you anything concerning His protection."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 1641