As the 116th Congress was sworn in Thursday, it made history for its diversity with a record number of women and minorities joining.

And the books lawmakers held or placed their hands on during their ceremonies proved to be just as unique.

A Christian Bible is not required for lawmakers when giving the oath to uphold their office. The Constitution expressly states that senators, congressmen and members of state legislatures “shall be bound by Oath or Affirmation, to support this Constitution; but no religious Test shall ever be required as a Qualification to any Office or public Trust under the United States.”

Here’s a look at some the unique books lawmakers – in both the House and Senate – held Thursday.

Ilhan Omar – grandfather’s Quran

One of the first Muslim women elected to Congress, Rep. Ilhan Omar, D-Minn., took the oath with her grandfather’s Quran, sharing a touching tribute to him on social media as well.

“As a kid, I acted as my grandfather’s translator at our caucuses and he was the one who first sparked my interest in politics. I wish he could be here to witness this historic moment, but he was there in spirit as I placed my hand on his Quran for the ceremonial swearing in,” Omar said on Instagram.

Rashida Tlaib – Thomas Jefferson’s Quran

House Speaker Nancy Pelosi of Calif., poses during a ceremonial swearing-in with Rep. Rashida Tlaib, D-Mich., sixth from right, on Capitol Hill in Washington, Thursday, Jan. 3, 2019, during the opening session of the 116th Congress. (AP Photo/Susan Walsh)

Rep. Rashida Tlaib, the first Palestinian-American woman elected to Congress, also used the Quran during her ceremony – one that is more than 280 years old. Tlaib, from Michigan, chose to use former President Thomas Jefferson’s English translation book from 1734.

According to Smithsonian Magazine, Jefferson had an interest in religion and most likely obtained the Quran while he was studying law.

Martha McSally – Bible recovered from USS Arizona

Vice President Mike Pence administers a ceremonial Senate oath during a mock swearing-in ceremony to Sen. Martha McSally, R-Ariz., Thursday, Jan. 3, 2019, in the Old Senate Chamber on Capitol Hill in Washington. (AP Photo/Manuel Balce Ceneta)

Sen. Martha McSally, R-Ariz., told Vice President Mike Pence the small Bible she chose to hold had been recovered from an unknown sailor aboard the USS Arizona, which was bombed during the attack on Pearl Harbor.

The Bible was on loan from the University of Arizona, she said.

New Sen. Kyrsten Sinema and McSally are the first female senators to represent Arizona. McSally was also the first female combat pilot in the Air Force where she eventually rose to the rank of colonel.

Kyrsten Sinema – law book

Vice President Mike Pence administers the Senate oath of office to Sen. Kyrsten Sinema, D-Ariz., during a mock swearing in ceremony in the Old Senate Chamber on Capitol Hill in Washington, Thursday, Jan. 3, 2019, as the 116th Congress begins. (AP Photo/Andrew Harnik)

Sen. Kyrsten Sinema, D-Ariz., held a law book which contained copies of the U.S. and Arizona constitutions during her oath, a spokesperson told The Arizona Republic.

“Kyrsten always gets sworn in on a Constitution simply because of her love for the Constitution,” spokesman John LaBombard said of the former congresswoman.

Mitt Romney – father’s Bible

New Utah Sen. Mitt Romney said he used his father’s Bible for his ceremony. His father served as Michigan's governor and as the Secretary of Housing and Urban Development during the Nixon administration.

“He inscribed a message in it each time he took the oath of office, and I did the same today,” Romney said.

The Associated Press contributed to this report.