Come now, you who say, "Today or tomorrow we will travel to such and such a city and spend a year there and do business and make a profit."
You don't even know what tomorrow will bring-what your life will be! For you are a bit of smoke that appears for a little while, then vanishes.
Instead, you should say, "If the Lord wills, we will live and do this or that."
But as it is, you boast in your arrogance. All such boasting is evil.
So, for the person who knows to do good and doesn't do it, it is a sin.