Fussilat 41:46

Man AAamila salihanfalinafsihi waman asaa faAAalayha wamarabbuka bithallamin lilAAabeed

Whoever does righteousness - it is for his [own] soul; and whoever does evil [does so] against it. And your Lord is not ever unjust to [His] servants.

If someone acts righteously, he does so for the benefit of his own soul, and if someone commits evil, he does so against it. Your Lord is not unjust to His servants.