Who was the first to shoot an arrow for the sake of Allah?

The first to shoot an arrow in the way of Allah was Sa'd ibn Malik (Ibn Abi Waqqas), may Allah be pleased with him. This occurred during the expedition (sariyyah) of Ubaidah ibn al-Harith ibn Abd al-Muttalib, which was the first expedition dispatched by the Messenger of Allah, peace and blessings be upon him, in the first year of the Hijra.