Sayyiduna Amr bin Abasah (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Whoever shoots an arrow at the enemy, whether it hits the target or misses, will have a reward equal to freeing a slave."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18510