You Do Need power plug adapter while traveling from Israel to Lebanon.

Here is Why You Need An Adapter

The outlet and plug type used in Lebanon are C, D and G and in Israel are C and H. This is how they look like.

Israel

In Israel, outlets of type C and H are in use.

Type C

Type H

Lebanon

In Lebanon, outlets of type C, D and G are in use.

Type C

Type D

Type G