Menstruation and charging interest
For example, today's first reading (Ezekiel 18:1-10, 13b, 30-32) lists things that the virtuous man does not do, including such things as having "relations with a woman in her menstrual period" and lending money at interest.
It is easy, of course, to brush off such admonitions as only pertaining to the Mosaic covenant or a particular time and place - irrelevant to our own lives. After all, we may say, we are not Jews and we live in an economic frame of reference that is very different from ancient times.
But it is dangerous to dismiss any Scripture out of hand.
To be sure, some Old Testament admonitions require very careful exegesis, to be done within the full context of the deposit of faith and with the help of the Holy Spirit, in order to understand their applicability in a definitive and detailed way.
But in a more general way and on a more personal level, it is always worthwhile to search for meaning within Scripture rather than dismiss it out of hand.
In the present example, we may ask ourselves: are we respectful of God's gift of sexuality and (if we are married) respectful of our spouse, or do we focus on our own desires and selfish "needs"?
Likewise, are we narrow-minded and short-sighted in our business decisions, violating both ethics and long-term business sense?
We must respect ourselves.
We must respect others.
We must respect Scripture.
Most of all, we must respect God.
(from an earlier post)