´Jundub bin Sufyan narrated that :` the Prophet said: "Whoever prays the Subh then he is under the protection of Allah's covenant, so do not be treacherous with Allah in his covenant."
Hadith ReferenceSunan at-Tirmidhi / The Book on Salat (Prayer) / Hadith: 222
Hadith Gradingالألبانی:صحيح، التعليق الرغيب (1 / 141 و 163)