The Messenger of Allah ﷺ said, "Standing guard at the frontier for a day and a night is better than fasting and praying through an entire month. If a man dies while engaged in it, the deeds he used to perform continue to be credited to him, his provision continues to flow to him, and he is kept safe from the trial of the grave."
عن رسول الله ﷺ أنه قال: رباط يوم وليلة خير من صيام شهر وقيامه، وإن مات جرى عليه عمله الذي كان يعمله، وأجري عليه رزقه، وأمن الفتان.
Muslim narrated it in the Book of Leadership (1913) from Abdullah bin Abdul-Rahman bin Bahram Darimi, who said, Abu Walid Tayalisi narrated to us, who said, Layth, meaning Ibn Saad, narrated to us, from Ayub bin Musa, from Makhul, from Shurahbil bin Simt, from Salman, and he mentioned it.Abu Ubayda bin Jarra wrote to Umar bin Khattab mentioning to him the gatherings of the Romans and what he feared from them, so Umar bin Khattab wrote back to him, "Now then, whatever hardship befalls a believing servant, Allah will bring relief after it, and hardship will never overcome two eases, and Allah Almighty says in His Book, "O you who believe, be patient, and vie with one another in patience, and stand firm, and fear Allah, that you may succeed" [Al Imran 3:200]."Malik narrated it in the Book of Jihad (6) from Zayd bin Aslam, who said, Abu Ubayda wrote, and he mentioned it. There are other hadiths with the same meaning in the Book of Jihad.The more fitting of the two meanings is, be patient in obedience and in refraining from what is forbidden, and vie with one another in patience against the harm of the polytheists and the enemies of Islam, and stand firm, meaning, keep yourselves ready in guarding the borders of the Muslim lands. And alongside these righteous deeds, do not forget the fear of Allah, for it is the key to success in this world and the next.As for what was narrated from Dawud bin Salih, who said, Abu Salama bin Abdul-Rahman said, "O son of my brother, do you know regarding what this verse was revealed, "Be patient, and vie with one another in patience, and stand firm" [Al Imran 3:200]?" He said, I said, No. He said, "O son of my brother, I heard Abu Hurairah say, In the time of the Prophet ﷺ there was no military campaign in which one stood firm, rather it was waiting for one prayer after another." This is daif.Ibn Mubarak narrated it in Zuhd (389), and through his route, Hakim (2/301) and Wahidi in Asbab Nuzul (page 135) narrated it, from Musab bin Thabit bin Abdullah bin Zubayr, who said, Dawud bin Salih narrated to me, and he mentioned it. Hakim said, "Its isnad is sahih."I say, it contains Musab bin Thabit, whom the majority of the scholars have graded daif, yet despite that Ibn Hibban mentioned him in Thiqat (7/478), just as he also mentioned him in Majruhin (1068) and said, "He is among those who narrate abnormal reports on their own authority from well-known narrators, and when this became frequent from him, he deserved that his hadith be avoided."