Musnad Ahmad 779:2

'Abd al-Wahhab narrated to us, from Sa'id, from Qatadah, from Salim ibn Abi al-Ja'd al-Ghatafani, from Ma'dan ibn Abi Talhah al-Ya'mari, from Abu Najih al-Sulami, who said: We besieged the fortress of Ta'if with the Prophet, may Allah bless him and grant him peace, and I heard the Messenger of Allah, may Allah bless him and grant him peace, say: "Whoever shoots an arrow in the way of Allah, and it reaches its target, he has a degree in Paradise." A man said: "O Prophet of Allah, if I shoot and it reaches its target, do I have a degree in Paradise?" He said: "Yes." So he shot and it reached its target. He said: "And I reached [the target] that day with sixteen arrows," and he mentioned the rest of its meaning.