The ultimate reason for avoiding the evil act is that it is harmful, not friendly, to one's being. (faith.org.uk)
39:28 — An Arabic Quran, without any crookedness (therein) in order that they may avoid all evil which Allah has ordered them to avoid, fear Him and keep their duty to Him. (religion.blogs.cnn.com)
Nor does he suggest that we should avoid evil merely because we shall otherwise suffer for it hereafter. (religion-online.org)