Explanation

Whoever learns archery (shooting arrows) or the like, such as shooting with bullets in our present time, for the sake of Allah, then stops practicing it, has indeed exposed himself to bearing a sin for that and has strayed from the guidance of the Prophet (may Allah's peace and blessings be upon him). The narrator used "is not one of us", and "has indeed disobeyed" because he was uncertain of the exact wording of the Prophet (may Allah's peace and blessings be upon him).