Amos 5:12 For I know your manifold transgressions and your mighty sins: afflicting the just and taking bribes; diverting the poor from justice at the gate.
No matter how you look at it, God is omniscient: at means that God knows everything. When we do bad things against others we are doing it in front of God because He knows, He sees and He hears everything.
We may overcharge people, take more than we should, say we can’t when we can, say no just to spite others; but we do this all with God watching. This is us sinning against God.
We need to admit that we do get things wrong, ask God to forgive us and then try to not go back to doing that again. That is God’s will for us.