Asking for a friend.
He does not hold any dual citizenship and only has a Lebanese passport. I am well aware of the diplomatic tensions these two countries hold but I was under the impression Israel did not have any restrictions on who could visit. However, I've seen contradictory answers online.
I suspect he might be questioned upon arrival. To makes things simpler, he's been living in Paris for years now and has no ties to anyone involved in politics in Lebanon.
Can he visit Israel with only a Lebanese passport? Also, even if he asks the Israel customs not to stamp his passport, can Lebanon find out he's been in Israel? Can he get in trouble when he decides to visit Lebanon?