THE ISRAELIS HAVE just done something truly amazing and commendable. At a moment when every other nation in the world is going bananas looking for ways to reduce dependence on foreign sources of energy, the Israelis have voluntarily abandoned the one source of oil under their control. The big Alma oil field in the Sinai, which they developed and brought into production to supply 20 percent of their needs, was quietly returned to Egypt as scheduled under the terms of the Israeli-Egyptian peace treaty. A little solar energy aside, Israel is now completely at the mercy of others for its energy supplies. Its debt is already murderous; the new step will raise its energy bill by perhaps half a billion dollars a year.

Israel has never had easy going in energy. It has yet to find significant resources on its own soil. It has never been able to buy oil from Arab producers. The change of regime in Iran cut it off from its longtime principal source. Only one country, Mexico, now openly sells oil to Israel, which must otherwise deal with sources or middlemen that might halt the business -- not, after all, a very large business -- if it were publicized. Israel has a commitment from Egypt to sell a certain amount of oil at (for the first year only) a certain price, but this commitment can be no firmer than the overall state of Israeli-Egyptian relations, and there are high hurdles -- specifically, the Palestinian question -- just a short distance down the road. The United States has undertaken to be Israel's supplier of last resort for a period of years, but that, too, involves political costs.

Prime Minister Menachem Begin is harshly criticized by some Israelis for accepting a peace treaty requiring the yielding of the oil wells. They say he is inviting an about-face by Cairo once a bit more of the Sinai, including some important passes, is returned. For what are, after all, gestures to Israel that an Egyptian leader could reverse overnight, Israel is giving up elements of the most tangible sort; territory, military bases and position, towns and farm communities housing 10,000 people, and now oil. This criticism, it should be added, reflects anxieties shared in greater or lesser measures by almost every Israeli.

Mr. Begin does not deny there is a risk. He says, correctly and corageously, its a risk worth taking. Whatever may be said about his approach to the Palestinians, he deserves high respect for making good on his peace treaty with Egypt. The most notable proof of his conviction so far is perhaps that as the moment of truth on oil arrived, he did not flinch.