Don't leave home without it. That has a different meaning here in Israel. What is more American than just taking your credit card when you know you aren't driving and probably won't be needing cash. ? How about an ID of some sort or even a passport.
We spent the afternoon at the Israeli Museum and an ID would have been a good idea. I made the decision not to carry anything other than my credit card. Not a good idea in a country where identification is important. Luckily my daughter and grandchild could
vouch for us. We do look sorta suspicious, come to think of it.