"Thou shalt not rejoice when your enemy falls." Thus are we commanded by the book of Proverbs. It's a command that is not always easy to carry out. For example, when it concerns Abu Nidal, who according to the news is currently hospitalized in Egypt in a terminal condition.

Abu Nidal murdered the Palestinian peace hero Issam Sartawi, who was like a brother to me. He murdered the Palestinian peace hero Said Hammami, a man I loved and admired. He murdered Abu Iyad, with whom I had planned peace actions before it was fashionable to do so. Abu Nidal threatened to murder me as well.

At the beginning of the year 1984, Sartawi and I appeared in a large public gathering in London. We arrived there under heavy security from Scotland Yard, after a lot of soul-searching. Sartawi knew that he was risking his life. A bloc of Abu Nidal followers sat in the auditiorium, disrupting his every sentence. An opposing bloc of Meir Kahane followers disrupted every sentence of mine. At one point Sartawi yelled out: "Blessed be! Now you have both formed an alliance! I congratulate you!" (I recorded the exchange and someday, when the museum of peace is built, I will donate this recording to it.)

The next day a London newspaper published an announcement that Abu Nidal had sentenced three people to death: The CIA agent Yasser Arafat, the Mossad Agent Issam Sartawi, and the CIA and Mossad Agent Uri Avnery. A few days later Sartawi was murdered.

Previously, we had spent dozens of hours analyzing the phenomenon called Abu Nidal. Again and again we tried to determine whom he was working for. Sabri Al Banah, who calls himself Abu Nidal ("the father of the struggle"), was born in Jaffa. He grew up as a refugee in Saudi Arabia, and worked there as a lowly laborer -- a class scorned in that rich country. When he ascended in the Fatah hierarchy, he felt even more humiliated and insulted, because most of the leaders of the organization were college graduates. It was evident that a tremendous amount of frustration and rage were accumulating in him.

When Abu Nidal was sent as a Fatah emissary to Iraq, he established contact with the Iraqi Intelligence Service. Following his new masters' instructions, he rebelled against Arafat, left the Fatah organization and established his own group: "Fatah -- the Revolutionary Headquarters." But Abu Nidal was not content with serving Iraq. In the course of the years, he served many masters, at times simultaneously. When there was a severe conflict between Baghdad and Damascus, he worked for both. He also served Libyan interests.

Sartawi added another potential employer to the list: Israel. Cicero's famous question: "Cui Bono?" ("Who benefits from it?") led Sartawi to conclude that the sole beneficiary of Abu Nidal's actions was the Israeli propaganda machine. For instance: When the PLO was working desperately towards international recognition and sympathy, Abu Nidal blew up synagogues and Jewish orphanages in Europe, in addition to murdering travelers at airports. The international media (and of course the Israeli media), which paid no attention to the nuances, accused Fatah of masterminding all the above.

Matters reached their peak in 1982. The entire world knew that Ariel Sharon wanted to invade Lebanon. I myself published in "Ha'Olam Hazeh" a detailed outline of the planned assault, from Sharon's own words to me (but without attribution). Sharon wanted to install a Christian Maronite dictator in Lebanon under Israel's auspices and to chase the Palestinians out of Lebanon and into Syria (and from there to Jordan, where they would topple the Jordanian monarch and establish a "Palestinian state" in its place). All that Sharon lacked was an excuse for a war, because Arafat had meticulously adhered to the cease-fire on the Lebanese border, agreed to with American negotiations. For an entire year the area was free of any incidents.

In May of 1982 Sharon met with General Alexander Haig, then the American Secretary of State, and asked for his approval of the invasion. Haig granted it, with the stipulation that the assault must come only after "a serious provocation, recognized as such by the entire world." A few days later, Abu Nidal made an attempt to assassinate the Israeli Ambassador in London, Shlomo Argov. The assassin was Abu Nidal's cousin, and the flawed nature of the attempt was evidence that it had been hastily planned. At a cabinet meeting, when the invasion was authorized, the head of the General Security Service noted that it was not Arafat who made the assassination attempt on Argov, but, in fact, his arch-nemesis, Abu Nidal. Begin cut him off, and the Chief of Staff, Rafael Eitan, commented: "Abu Nidal, Abu Shmidal, all of them are PLO!"

Sartawi was convinced that Israel had contracted with Abu Nidal to carry out the assassination. In his opinion, Abu Nidal was nothing but a terrorist contractor who offered his services to anyone. Sartawi did not have conclusive proof in his hands, but the coincidences were impressive. Even earlier, in January of 1978, Abu Nidal murdered Said Hamami, also a native of Jaffa, and a remote relative of Abu Nidal, which did not help him any. Arafat sentenced Abu Nidal to death, but the latter proved to have a remarkable talent in concealing his whereabouts. There is only one known photo of the man, and Sartawi told me that it is not Abu Nidal's picture at all but that of his bodyguard.

Once, during a rare interview, Abu Nidal was asked by the German weekly "Der Spiegel" how he would propose to deal with Israeli peace activists such as myself. "Uri Avnery should go back to Germany," he responded in an rare display of generosity.