question #1 Sahih al-Bukhari 2826, Book 56, Hadith 42 : How does Allah’s mercy and forgiveness manifest in the context of two individuals who were once enemies?

Allah’s Messenger (ﷺ) said, “Allah welcomes two men with a smile; one of
whom kills the other and both of them enter Paradise. One fights in
Allah’s Cause and gets killed. Later on Allah forgives the ‘killer who
also get martyred (In Allah’s Cause).”