question #1 Sahih al-Bukhari 2839, Book 56, Hadith 55 : How does intention and circumstance affect the reward of participating in a good deed?

While the Prophet (ﷺ) was in a Ghazwa he said, “Some people have remained behind us in Medina and
we never crossed a mountain path or a valley, but they were with us (i.e. sharing the reward with us),
as they have been held back by a (legal) excuse. ”