Psalm 109:17 shows us “two sides of the coin” of sin, both sins of “commission” and of “omission”: “He also loved cursing, so it came to him. And he did not delight in blessing, so it was far from him”. The man described here sinned by cursing others, but that was not the extent of his transgression. He also did NOT bless people; that sin of omission was equally a sin. Committing a particular evil is obviously wrong; but as James 4:17 reminds us, NOT doing the good we know to do is also a sin: “Therefore, to one who knows the right thing to do and does not do it, to him it is sin.”
Many times our greatest fault lies not in what we did; but in what we did NOT do … far more than we often realize. Many in fact consider themselves to be in pretty good standing with God because there is a whole long list of things that they are not doing: murder, immorality, certain vices, etc. But what they do not realize is that there is just as long a list – in fact, most likely much longer! — of things they are NOT doing, which is condemning them! It is not enough just “not to curse”; Psalm 109 reminds us that it is our responsibility TO bless. Not murdering people doesn’t satisfy our responsibility towards them; God has commanded us to love them. It is not enough to just “not commit adultery”; you are positively to love your spouse. If you ever think that you are doing well spiritually because of all the things you are “NOT” doing, you probably need to look on the other side of the coin!