Israeli citizen entering Ben Gurion without Israeli passport

Getting to Israeli border control

As an Italian citizen you're allowed to enter Israel visa-free, therefore the airline won't mind letting you on the plane. However if asked (by the airline) about your stay, don't mention anything about working or living in Israel, as in this case they would like to see proof of you being allowed to do so, which you won't have. Simply state that you're going for vacation and will come back to the EU afterwards.

Sometimes you might also be questioned by Israeli government officials before you board your plane - in this case you should of course lay out the facts as-is and explain that you've forgotten your Israeli passport. Expect to get some extra questions, but you should be fine overall.

Entering Israel

Once you arrive at the border post, head for the "Israeli citizens" line and immediately mention that you forgot your passport. It is illegal to enter Israel on foreign documents, so they'll need to look you up in the citizens database before letting you enter the country. I'd expect an hour delay at most while this process is ongoing, but you should be fine in the end - Israel isn't known for turning away their own citizens.

There's getting on the airplane...

They won't let you on the airplane... Unless your papers are in order for you to enter Israel.

As far as the airline is concerned, you're an Italian. Now it looks like, as a citizen of the EU, Israel does not require un italiano to have a visa. So you should be all right.

The consequence for the airline is that they must pay a hefty fine, and then, fly you back to a country where you can't be refused, i.e. The EU. They don't know that you can get into Israel on the strength of your citizenship, and they won't take your word on it. However the airline is not responsible if your papers are in order yet you blow the entry interview.

...Then there's getting into the country

I am assuming that as an Italian, you would not blow your entry interview, and so would be admissible per se. However your ultimate trump card is that you are, in fact, an Israeli citizen. You need to mention that, and that you erred and left your Israel passport in Italy, and make them know you know that was a mistake. That'll save you a lecture. I would expect their response to be "we don't care, because you're admissable as an Italian, but next time have the right passport".

If your admission had to hang entirely on your Israeli citizenship (meaning they wanted to refuse you as an Italian), then you should expect a delay at immigration, whilst they do whatever they do to verify your citizenship. I would imagine the Israeli security services will be right on top of such things.

Technically they can't refuse you entry and deport you, but they can detain you while they investigate.