JERUSALEM—Decades of ethnic tension ceased instantaneously Monday when Israeli prime minister Ehud Olmert and Palestinian president Mahmoud Abbas shook hands over a comprehensive agreement to return a faded green lawn mower first borrowed by Israel in 1949.

The Israeli prime minister apologizes for not refilling the tank first.

The historic accord, whose sole term was the long-awaited return of the hotly contested lawn-care device, was signed amid cheers and applause from representatives of both nations. Celebrations were reported across the Middle East, as Jews and Muslims came together by the thousands to rejoice in the streets.

The return of the disputed item brings an end to half a century of violence and bloodshed in the borrowed-lawn-mower-torn region.

"With the return of the mower to the cherished homeland, the healing process can finally begin," Abbas told a cheering crowd of more than 100,000 Israelis and Palestinians who gathered at the border to watch a lawn mower handover many thought would never take place in their lifetimes. "Now, I call on all Palestinians to cease all aggression toward our neighbors, so that we may live harmoniously alongside them while finally getting started on a lawn that has been badly in need of cutting for three generations."

The lawn mower, a rusty two-stroke 1943 Lawn Boy, holds a value that is largely symbolic and, due to its poor condition, has not actually been used by Israeli Self-Groundskeeping Forces since 1989. It reportedly starts only after repeated yanking on its pull-cord, requires liberal sprays of starter fluid, belches thick acrid smoke, must be laboriously pushed due to a faulty drive roller, and has no accompanying grass-clipping collection bag. But geopolitical experts agree that it is the principle of the lawn mower, more than the machine itself, that has led to 60 years of airstrikes, rocket launcher attacks, and suicide bombings, with countless dead and tragically poor yard maintenance on both sides.

"A loaner is a loaner, whether it's a rusted-out hunk of junk or not," said Dr. Sayid Al-Habib, a noted Palestinian diplomat. "Sure, it leaks oil, and yes, we were probably going to throw it out anyway, but that is not the point. When you borrow something, you return it."

The mower was originally lent to Chaim Weizmann, the first president of Israel, in November 1949 as a good-faith gesture by Palestinians seeking to reach out to the people who had appropriated 80 percent of their land and wished to cut the grass growing there. However, when the mower had not been returned by the next spring, and Palestine's own lawn began to get out of control, social unrest grew along with it.

"The conflict had gone on for so long that many of us had forgotten what we were fighting about in the first place," Israeli spokesman Mark Regev, flanked by cheerful members of the now-defunct Palestinian Islamic Jihad, told reporters at press conference in downtown Jerusalem. "Though at first Israel had every intention of returning the mower, some hard-liners in the Knesset objected to doing so until Palestine returned our hedge clippers. Then there was the matter of several extension cords which were borrowed without asking by various pan-Arab power blocs. Soon, as you all know, the situation spiraled out of control."

"But now everything is totally fine," he added.

By the late 1950s, the lawn mower had become a central point of dispute between the two groups. In 1964, Daoud Mikhail founded the Palestinian Lawnmower Organization around the central tenet of the "right of return" of the mower from Israel. When Israel refused to recognize the PLO, frustrated Palestinians resorted to chopping off the branches of Israeli trees that extended over Palestinian lawns. In response, Israel razed 40,000 acres of olive groves, beginning a cycle of escalating violence that would include Palestinian suicide bombings, Israeli bulldozing of Palestine's lawn, the erection of a much larger fence between the two nations' properties, and the 1973 Yom Kippur War.

The dispute also resulted in the 2003 death of an American pro-Palestinian activist who laid down in front of the lawn mower as an Israeli Army edger-trimmer squad cut disputed grass. Refusing to move when ordered, he was tragically mulched.

"Now that Israel has finally returned this mower, we look forward to friendly relations between our two nations for all time," Palestinian negotiator Saeb Erekat said at the United Nations Monday. "We will immediately return the disputed Israeli Frisbee that landed on our roof decades ago, invite the Israelis to join the Palestinian Neighborhood Organization, and act in concert with them to demand the return of the basketball stolen by Syria in 1979."