Jabir (May Allah be pleased with him) reported:
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].

وعن جابر رضي الله عنه قال: كنا مع النبي ﷺ في غزاة فقال: "إن بالمدينة لرجالا ما سرتم مسيرًا، ولا قطعتم واديًا إلا كانوا معكم حبسهم المرض"