I am teaching this to my students with regard to the fact that Yosef was harmed by the shevotim while carrying out the mitzvah of kibbud av. Whilst the meforshim there deal with why he was not protected in this specific case, how would I answer the fact that there are countless examples of people who were harmed through the doing of a Mitzva.
Aliza, London England
Shalom,
There are several basic ways of answering your question that I can think of. Without going into great detail, we may suggest as follows:
1. A Mitzvah will protect the person carrying it out only when it is performed with a positive intention, and not if he is doing it for personal motives (e.g. to put on a show of righteousness).
2. Sometimes what seems to be harmful is really to the person's benefit, even to the point of saving his life. (Just recently a Jew in Israel was stabbed by a terrorist, and while being treated for the wound in the hospital a cancer was discovered, in time for treatment, of which no one was previously aware.)
3. The person may be destined, for example, to die at that time anyway, and the fact that he was performing a Mitzvah turns him into person who died "Al Kidush Hash-m." (Some say this about the Kedoshim who were killed while Davening here in Har Nof last year.)
4. If one has sinful thoughts while performing the Mitzvah, the Mitzvah may well not save him.
5. The apparent harm might turn out to be part of a chain of events that are really beneficial to the perpetrator and/or to others, as was the case by Yosef. (This reason is slightly different from #2.)
Kol Tuv,
E. Chrysler