Sunan At-Tirmidhi

Narrated Abu Najih As-Sulami: I heard the Messenger of Allah (ﷺ) say: ""Whoever shoots an arrow in the cause of Allah, then he has the reward of freeing a slave."" [Abu 'Eisa said:] This Hadith is Hasan Sahih. Abu Najih is 'Amr bin 'Abasah As-Sulami, and 'Abdullah bin Al-Azraq is 'Abdullah bin Zaid