Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrated that the Messenger of Allah (peace and blessings be upon him) said: "At the time of every prayer a caller is sent, and he says: O children of Adam! Rise and extinguish the fire that you have kindled against yourselves. So they rise and purify themselves, and their sins fall away from their eyes; and they pray, and what is between the two is forgiven for them. Then after that they kindle (the fire of sins) again. Then when the time of Zuhr comes, he calls out: O children of Adam! Rise and extinguish the fire that you have kindled against yourselves. So they rise, purify themselves and pray, and what is between the two is forgiven for them. Then when the time of Asr comes, it is likewise; then when the time of Maghrib comes, it is likewise; then when the time of Isha comes, it is likewise. So they go to sleep in a state in which they have been forgiven." Then the Messenger of Allah (peace and blessings be upon him) said: "So the one who travels by night may be travelling in goodness, and the one who travels by night may be travelling in evil."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10214