Jbr bin 'Ubaid'h جبر بن عبيدة · The Book of Jihad

"Whoever guards Ribat (the frontier) for one day and one night, will be given a reward like that for fasting and praying Qiyam for a month, and whoever dies at Ribat (guarding the frontier) will be rewarded, and he will be given provision, and he will be kept safe from Al-Fattan." According to As-Sindi, the preferred pronunciation is Al-Fattan, plural of Fatan refering to Al-Munkar and An-Nakir, while Al-Fattan would refer to Ash-Shaitan or the like, among the punishment of…

"I heard the Messenger of Allah (ﷺ) say: 'Whoever guards Ribat (the frontier) in the cause of Allah for one day and one night, he will have (a reward) like that of fasting and praying Qiyam for a month. If he dies he will continue to receive reward for what he did, and he will be kept safe from Al-Fattan, and he will be given provision.'"