By the One in Whose hand my soul is, if you were not to commit sins, Allah would replace you with people who would commit sins and then seek forgiveness from Allah, the Almighty, who would then forgive them. [Muslim]

«والذي نفسي بيده، لو لم تذنبوا، لذهب الله بكم، وجاء بقوم يُذْنِبُونَ، فيستغفرون اللهَ تعالى، فيغفر لهم». [مسلم]