Lesson 1 When someone asks you a question, they are making themselves vulnerable by admitting they do not know something. To say to someone "what, you don’t know such a simple thing?" causes onaas dvarim (pain with words). Such comments will not make the person any wiser, just intimidate them and prevent them from asking for vital information in the future. Lesson 2 Answering someones questions is an act of kindness, when we recognize this, we can be prevented from feeling irritated at the questioner.
(Lessons taken from The Power of Words by Rabbi Zelig Pliskin)
Important Numbers
