Sharhabeel bin Simt narrates: Once, Sayyiduna Salman al-Farsi (may Allah be pleased with him) passed by him while he was performing guard duty. Sayyiduna Salman (may Allah be pleased with him) said: I heard the Prophet Muhammad (peace and blessings be upon him) say: "Whoever dies while standing guard, his deeds continue as before, and he is protected from the trials (of the grave), and he is provided sustenance (in the Hereafter)."
Hadith Referenceصحیح ابن حبان / كتاب السير / 4626
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - انظر ما قبله.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح