حَدَّثَنَا مُحَمَّدُ بْنُ إِسْمَاعِيلَ بْنِ سَمُرَةَ، حَدَّثَنَا مُحَمَّدُ بْنُ يَعْلَى السُّلَمِيُّ، حَدَّثَنَا عُمَرُ بْنُ صُبْحٍ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ عَمْرٍو، عَنْ مَكْحُولٍ، عَنْ أُبَىِّ بْنِ كَعْبٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ لَرِبَاطُ يَوْمٍ فِي سَبِيلِ اللَّهِ مِنْ وَرَاءِ عَوْرَةِ الْمُسْلِمِينَ مُحْتَسِبًا مِنْ غَيْرِ شَهْرِ رَمَضَانَ أَعْظَمُ أَجْرًا مِنْ عِبَادَةِ مِائَةِ سَنَةٍ صِيَامِهَا وَقِيَامِهَا وَرِبَاطُ يَوْمٍ فِي سَبِيلِ اللَّهِ مِنْ وَرَاءِ عَوْرَةِ الْمُسْلِمِينَ مُحْتَسِبًا مِنْ شَهْرِ رَمَضَانَ أَفْضَلُ عِنْدَ اللَّهِ وَأَعْظَمُ أَجْرًا - أُرَاهُ قَالَ - مِنْ عِبَادَةِ أَلْفِ سَنَةٍ صِيَامِهَا وَقِيَامِهَا فَإِنْ رَدَّهُ اللَّهُ إِلَى أَهْلِهِ سَالِمًا لَمْ تُكْتَبْ عَلَيْهِ سَيِّئَةٌ أَلْفَ سَنَةٍ وَتُكْتَبُ لَهُ الْحَسَنَاتُ وَيُجْرَى لَهُ أَجْرُ الرِّبَاطِ إِلَى يَوْمِ الْقِيَامَةَ ‏"‏ ‏.‏

It wasnarrated that Ubayy bin Ka’b said: “The Messenger of Allah(PBUH)said: ‘For guarding the frontier for a day in the cause ofAllah,defending the Muslims, seeking reward, apart from in the monthofRamadan, there is a reward granted greater than worshipping for ahundred years, fasting and praying. Guarding the frontier for a dayinthe cause of Allah, defending the Muslims, seeking reward, in themonth of Ramadan, is better before Allah and brings a greater reward”– I think he said – “than worshipping for a thousand years,fastingand praying. If Allah returns him to his family safe andsound, no baddeed will be recorded for him for a thousand years, buthis good deedswill be recorded, and the reward for guarding thefrontier will cometo him until the Day of Resurrection.” Translation Not Available

Book Ref: Sunan Ibn Majah Book 24 Hadith 2768
Web Ref:  Sunan Ibn Majah Vol 4 Book 24 Hadith 2768