On the eve of his departure for the Middle East summit meeting at Camp David, Israeli Prime Minister Menachem Begin last night echoed the peace covenant made nine months ago by Egyptian President Anwar Sadat.

"Let us agree together: let us repeat together one in the ears of the other the most important announcement which you gave me, and which I returned: No more war. there will be no more war between us and the Egyptian people. Let us stretch out our hands to one another," Begin said.

In a nationwide address that his aides said was designed to set the tone of the peace talks starting Wednesday, Begin promised:

"I shall stretch out my hand to President Sadat and say that in Jerusalem and Ismailia you stretched out your hand and said that you were my friend. Let us renew that friendship . . . let us keep the friendship in spite of everything that has happened between Ismailia and today," the prime minister said. The two met in Ismailia last December.

But Begin stressed as he has repeatedly in recent days, that the renewed peace talks do not represent a last-gasp opportunity for peace in the Middle East.

"This, of course, is one of the important events of our time. (But) if people say this is a fateful meeting, we disagree. The fate of our people should not depend on any meeting - this meeting or any other," Begin said.

"Our people lived thousands of years before Camp David and shall continue to exist thousands of years after . . . There are no last opportunities or chances. There is always new opportunity," said Begin.

[In Tel Aviv, United Press International reported, nearly 30,000 demonstrators earlier called for Begin to seize "the last chance for peace." Most of the marchers were youths bused from kibbutzim, responding to the call of a fledgling peace movement.]

The prime minister, accompanied by Foreign Minister Moshe Dayan and Defense Minister Ezer Weizman and an 11-member negotiating team, is to leave early today for Washington.

Begin noted that direct negotiations for the Panama Canal treaties lasted 14 years and that intensive peace talks to end the Vietnam war lasted four years. He urged Egypt and the United States not to raise expectations to the level where a comprehensive Middle East peace treaty will be reached at Camp David.

Instead, Begin urged, the meeting should be viewed as a prelude to continued bargaining.

"Let us decide at Camp David that negotiations will be continued for a number of months, every day except Friday and Saturday, and we shall deal with the conditions of peace until both of us . . . can announce to the people that we concluded a peace treaty," Begin said.

His reference to Friday and Saturday was to the Jewish Sabbath and the Moslem holy day of prayer.

Begin assured his constituents that Israel's negotiations will safeguard the safety of our people," Begin said par-