so the fact is that it was not you but it was allah who killed them and it was not you when you threw but it was allah who threw it that he might cause the believers to successfully pass through this test. allah is allhearing allknowing.
فلم تقتلوهم ولكن الله قتلهم وما رميت إذ رميت ولكن الله رمى وليبلي المؤمنين منه بلاء حسنا إن الله سميع عليم