Musnad Ahmad Hadith 15763

Khubayb bin Abdur Rahman’s grandfather says that once I and a man from my tribe went to the service of the Prophet (peace be upon him) at a time when the Prophet (peace be upon him) was preparing for a battle. We had not accepted Islam until then. We said to the Prophet (peace be upon him): It is a matter of shame for us that our tribe is going for a battle and we do not participate with them, so we will also go with you. The Prophet (peace be upon him) said: Have both of you accepted Islam? We said: No. The Prophet (peace be upon him) said: We do not want to take help from polytheists against polytheists. Upon this, we accepted Islam and participated with the Prophet (peace be upon him). In that battle, I killed a man and he struck me a blow. Later, I married the daughter of that slain man, and she used to say: You will never forget the man who gave you this wound. And I used to say to her: You too will never forget the man who quickly showed your father the way to Hell.