Morsi sworn in as Egypt's president in Cairo ceremony

Egyptians wave national flags during a rally in support of president-elect Mohamed Morsi in Cairo's Tahrir Square on June 29.

• Mohamed Morsi will be sworn in Saturday
• He tells a packed crowd at Tahrir Square that his authority comes from all Egyptians
• He says he will fight to release political prisoners, including Sheikh Omar Abdel-Rahman

(CNN) -- Egypt's Mohamed Morsi will be sworn in Saturday as the nation's first democratically-elected president, a day after he pledged to be a leader of all people during an address at Cairo's Tahrir Square.

Morsi told a packed audience Friday that the people are the source of his authority as the country's first democratically-elected leader.

"The whole nation is listening to me," he said in Cairo, referring to political and military leaders, and citizens.

"There is no authority above the authority of the people.

The incoming president promised to protect the rights of all Egyptians, whether they voted for him or not.

Morsi 'salutes' all people of Egypt

"No rights will be taken from anyone who says no to me," he said.

The Islamist leader called being elected president a great honor. "I cherish this mission," he said.

At the end of his speech, Morsi referred to Sheikh Omar Abdel-Rahman, the blind Egyptian cleric serving a life sentence in the United States for a conspiracy conviction in the 1993 World Trade Center bombing.

He said he wanted to work to free political prisoners, which he said include Abdel-Rahman.

"Their rights will be on my shoulders, and I won't spare effort" to free them, he said.

His speech Friday echoed earlier promises he made insisting that he would not create a fundamentalist Islamic state.

Morsi leads the Freedom and Justice Party, the political wing of the Muslim Brotherhood, and some Egyptians were concerned about a shift toward an Islamic state.

"I will faithfully execute and preserve the republican system and respect for law and sovereignty," he said.

Morsi, 60, was declared president Sunday after he took 52% of the vote to 48% for Ahmed Shafik, the final prime minister to serve under President Hosni Mubarak before he was ousted.

During the historic campaign for president, Morsi said he would support democracy, women's rights and peaceful relations with Israel if he won.

"I will keep in touch with everyone, and I do not differentiate between supporters and opposition. I will seek advice from you and from Allah almighty," he said.