Riyad as-Salihin 1342

We accompanied the Prophet (ﷺ) in an expedition when he (ﷺ) said, "Some people have remained behind us in Al-Madinah, and we never cross a valley but they are with us. They share the reward with us because they have been held back by valid excuse."In another narration the wordings are: "...by any genuine excuse."In another narration the wordings are: "They are your partners in reward."[Al- Bukhari].