Hadith: Observing Ribāt (guarding the Muslim frontiers in the cause of Allah) for a day and a night is better than fasting and standing for night prayer for a whole month. If a person dies (while performing Ribāt), he will receive the reward for his righteous deeds perpetually, will receive his provision, and will be saved from the trials of the grave

عن سلمان الفارسي رضي الله عنه مرفوعاً: «رباط يوم وليلة خير من صيام شهر وقيامه، وإن مات جرى عليه عمله الذي كان يعمل، وأُجْرِيَ عليه رزقه، وأَمِنَ الفَتَّانَ».
[صحيح] - [رواه مسلم]

Salmān al-Fārisi (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: “Observing Ribāt (guarding the Muslim frontiers) for a day and a night is better than fasting and standing for night prayer for a whole month. If a person dies (while performing Ribāt), he will receive the reward for his righteous deeds perpetually, will receive his provision, and will be saved from the trials of the grave."
[Authentic hadith] - [Narrated by Muslim]

Explanation

Guarding the borders of Muslim lands for a day and a night protecting Muslims (from their enemies) is better than fasting for a month and standing for night prayer for a month. If a Muslim dies while in Ribāt in the cause of Allah, the reward for his good deeds will continue to be added to his account and not stopped. He will receive provision from Paradise, because he is alive in the Paradise of his Lord and will also enjoy the special privilege of being spared the questioning in the grave by the two angels, because he died while being on guard in the cause of Allah. It is worth noting that Ribāt is a part of Jihad in the cause of Allah, because it means staying at the borders to protect the Muslims from the disbelievers.