Jabir bin 'Abdullah al- ansari (may Allah be pleased with him) reported: We accompanied the Prophet peace and blessings of Allah be upon him in an expedition when he said, "there are some men in Al-Madinah who are with you wherever you march and whichever valley you cross. they have not joined you in person because of their illness." In another version he said: "They share the reward with you." [Muslim]
It is narrated by Bukhari, Anas bin Malik may Allah be pleased with him: We were coming back from the battle of Tabuk with the Prophet (peace and blessings of Allah be upon him) when he remarked, "There are people whom we left behind in Al-Madinah who accompanied us spirit in every pass and valley we crossed. They remained behind for a valid excuse".