Arab leaders at a summit here dispatched a delegation to Cairo yesterday in a dramatic last-ditch effort to dissuade Egyptian separate peace with Israel.

Sadat disdainfully refused to meet the four-man delegation and reitterated his earlier rejection of their offer of $5 billion annually for the next decade.

In a speech to the Egyptian parliament, Sadat said the summit delegates " will not meet me, and they will not meet any responsible official in Egypt.

"My message, let them hear it now, is that billions of dollars will not buy the will of Egypt, " he added to the cheers of Egyptian members of parliament.

The delegates, lead by Lebanese Premier Salim Hoss, were met by a junior protocol officer, driven to a downtown Cairo hotel for a brief rest and sent back to the airport within three hours.

Radical Arabs at the summit here led by the Palestinians, jubilantly welcomed Sadat's rejection. They predicted it would have the way for tough punitive measures against Cairo perhaps a total economic and political boycott of the Sadat government.

Observers were at a loss to explain now moderate Arabs allowed themselves to be maneuvered into accepting the predictably unsuccessful mission led by Hoss. Moderate Arabs admitted that it was their own Camp that suggested it.

Informed sources said the moderates, led by Saudi Arabia, were cornered by radicals challenging them to prove that Sadat was willing to forego a separate peace despite the growing burden of proof to the contrary.

" If indeed the radicals get their way here, their tactical victory will be in keeping with a long line of Arab summits which almost without exception have witnessed pro forma support for the most extreme positions on the table.

Aside from the Palestinians, other Arab governments only recently converted to the virtues of moderation - such as Syria and Iraq - appeared delighted with the day's happenings.

Earlier the moderates had argued against tough sanctions to punish Sadat's Egypt on grounds that Sadat had not yet signed the separate peace and that any threats here at the summit could only push him in that direction.

Sadat's rejection of the summit mission was a foregone conclusion, especially since it included high-powered officials from two of his strongest critics, Iraq and Syria.

The mission was announced as Arab moderates and radicals spent the summit's third day bogged down in discussions about how to thwart the Camp David agreements consecrating Egypt's defection from Arab world ranks.

But resolutions before the summit calling for an economic and political boycott of Egypt and removal of Arab League headquarters from Cairo are considered more likely to be adopted now that the Cairo mission has openly failed.

So far the conferees, in informal bilateral and formal plenary sessions, have agreed only to condemn the Camp David accords - judged incapable of achieving a comprehensive Middle East peace - and to establish a fund for front-line states facing the full brunt of Israel's superior war machine.

But any tradeoff between political stands and the money appeared far off. Reflecting failure to agree on such a tradeoff, the conference has yet to decide how much money should go to Syria, Jordan the Palestine Liberation Organization and Palestinians living inside Israeli-occupied territory.

Syria was reported demanding billion annually for a decade on grounds it deserved the same amount that Egypt had been allotted in the Iraqi proposal to Sadat.

But Sadui Arabia, Kuwait and other rich oil countries of the Arabian Peninsula appeared intent on diminishing that outlays or at least ensuring that their contributions represented leverage to achieve their conservative political demands.

Bedeviling the summit since the beginning were suggestions that it was being held either too early or too late. Critics argued that the summit should either have been held right after the Camp David agreements or after the Egyptian-Israeli treaty is actually in the knowledge that the spotlight was on them at a crucial moment, summit participants appeared eager to avoid any humiliating walkouts. The PLO spokesman, Abdul Mohsin Abu Maizer, blamed the United States for trying to torpedo the gathering by having " certain Arab countries " argue against clear condemnation of Sadat, rather than naming moderate Arab governments such as Jordan and Saudi Arabia.

One of the most radical Arab states, Libya, signaled its suspicions of such a conciliatory line by the absence of its head of state, Col. Muammar Quaddafi.

Syria's hard-line rhetoric also has been tempered by such factors as a desire to maintain Saudi financial largesse and preserve American diplomatic support.

Washington Post correspondent Thomas W. Lippman reported from Cairo:

In his speech to the Egyptian parliament, Sadat said, "We are on the threshold of restoring our confidence and dignity."

Egypt, he said, is" about to sign a peace agreement that will restore our full sovereignty (over the Sinai Peninsula) and guarantee to the Palestinians the restoration of their rights."

As for the summit meeting in Badlidad, he said, "How long will the fate of the Arab world be determined by emotionalism? Maybe their people accept this but I don't accept it, and the people of Egypt don't accept it."

Sadat gave no details about the status of the negotiations with Israel. Foreign Minister Boutros Ghali and First Secretary Osama Baz returned to Cairo last night to brief Sadat on the talks.

Baz told reporters that they expect to see Sadat today and return to Washington early in the week. He said there are some points on which no agreement has yet been reached in the Washington talks, but he did not say what they were.

It is safe to say, however, that on the basis of Sadat's remarks last night, a peace treaty is going to be signed without too much more delay and that whatever obstacles remain are not insuperable. Sadat, who appeared confident and vigorous, said Egypt is "building the edifice of peace" to democracy and to prosperity. It is the difficult road. but we have no alternative."

He added: "Egypt is not isolated and will not be isolated by anybody. Who are they who talk of isolating Egypt?"

As the Arab leaders assembled in the Iraqi capital must have known, the compositon of the delegation they sent to see Sadat virtually guaranteed that the mission would fail. The ranks of those sent were not high enough to oblige Sadat to receive them.

Beyond that, three of the four are associated with regimes to which Sadat feels bitter enmity. Hoss is seen here as a tool of Syrian President Hafez Assad, Sadat's former ally who has turned against him. Also on the delegation were Assad's information minister, Ahmed Iskander, and Tareq Aziz, a member of the ruling council in Iraq, a country that has vehemently opposed all Sadat's peace moves.

Only the fourth member, Ahmed Khalifa Suweidi, the foreign minister of the United Arab Emirates, represented a government or faction with which Egypt is on good terms.

According to Egypt's official Middle East News Agency, Sadat said later, "I am not prepared to receive anybody except kings and presidents.If they wish, I am prepared to receive them, welcome them, sit down and hold discussions with them."

It was clear even before the Baghdad summit that Sadat was not going to be deterred by whatever the delegates did there any more than he has been by previous Arab outcries against his peace initiative.

The Cairo press was unrestrained last week in heaping scorn on the participants, ridiculing their "empty slogans." Nevertheless, there is growing edginess and discomfort among some Egyptian officials about the extent to which Sadat is going it alone and the near unanimity of disapproval voiced by the participants at the Baghdad conference.

The confidence that other countries would follow Egypt's lead in entering into negotiations with the Israelis has been tempered with anxiety about how long Egypt can go on so openly defying the other Arabs. If Sadat shares any of this concern, however, he is not showing it.