Pecado de omisión
No sé como debo traducirlo...
4 Answers
Unlike the sin of commission (doing evil), it is failing to do right (doing nothing when you should have done something good).
Sins of commission: lying, stealing, raping, murdering, adultery, etc.
Sins of omission: not giving alms to the poor, not visiting the sick, not visiting the imprisoned, not preaching the gospel to the lost, etc.
You're talking about sins of omission, the Catholic idea I think.
Another way to look at is that It can be just as bad (a sin) to omit something as it is to say something wrong.