In less than two weeks, millions of Muslims around the world will gather in large congregations for prayer and festivities to celebrate one of the holiest of Muslim holidays, Eid al-Adha.

Throughout New Jersey local services will be held, and thousands will attend to pay tribute to Abraham's willingness to sacrifice his son on God's command. In Paterson, a crowd of more than 10,000 people are expected to attend one of four prayers sessions at one of the largest mosques in the state.

But this year, the day that marks the end of religious pilgrimages to Mecca may fall on the actual anniversary of 9/11, causing some concern about the security and safety of Muslims during the celebrations set in open areas or mosques. It would be the first time the holiday has fallen on the anniversary in the 15 years since the attacks.

"We are going to post additional security," said Imam W. Deen Shareef, the convener of the Council of Imams in New Jersey, whose congregation has raised concerns over the perception of the celebrations planned at Weequahic Park in Newark.

The start of the three-day holiday, also known as the Festival of Sacrifice, is based on the Islamic lunar calendar and occurs about 11 days earlier every year. The celebrations begin 10 days after the new moon is spotted, which religious leaders expect to see Thursday or Friday.

"We don't control the day [Eid al-Adha] is going to be observed," Shareef said. "The most important thing is that the message is not misconstrued that we are celebrating 9/11."

Shareef said he is worried about an "irrational reaction" to the festivities in the park, where he expects up to 3,000 members to attend.

In the South Jersey, religious leaders said they have little concern of a negative response from their communities, and may not even request security from local law enforcement.

"We do not have much concern," said Muhammad Ayub, a spokesman for the Muslim Community Organization of South Jersey, who expects between 4,000 and 5,000 worshippers to attend services at Atlantic City High School. "We have never had a problem. We feel very safe."

Although Morshad Saami Hossain, the Imam and director of Muslim American Community Association in Voorhees, said his congregation is not worried about the holy day falling on Sept. 11, it will send out informative messages to the community.

"We just want to clarify things, letting the public known that it is not in celebration of 9/11," Hossain said.

Omar Avvad, the president of the Islamic Center of Passaic County, said he was more concerned with the anti-Islamic rhetoric on the national level posing more of a threat to people's safety than the holy day falling on 9/11.

Last year, Republican presidential nominee Donald Trump claimed that thousands of Muslims in Jersey City celebrated after the fall of the Twin Towers in 2001, and would later propose a ban on all Muslims from entering the United States. Although an investigation by NJ Advance Media found Trump's broad claim to be baseless, small pockets of people were witnessed cheering.

Shareef said his congregation will work with the Essex County Sheriff's Department to add extra security to the services, which will include two prayer sessions and festivities primarily for children in the park.

Bill Maer, a spokesman for the Passaic County Sheriff's Department, said there was no credible threat to any services, but said its faith-based security program will provide extra officers to ensure that everyone remains safe.

Avvad said his community was aware of the issues that may arise if the holy day falls on Sept. 11.

"We are not completely unaware of the date and the gravity of it, and our thought and prayer will go out to all those affected by [9/11]," said Avvad, whose congregation will also add additional security for its four indoor prayer services.

"The [Passaic County] Sheriff's Department is usually very cooperative and supportive," he said.

Ayub praised the local community and law enforcement for their acceptance to his mosque Al-Taqwa over the years.

"We feel very proud to be part of this community," he said. "We are proud Americans."

Craig McCarthy may be reached at CMcCarthy@njadvancemedia.com. Follow him on Twitter @createcraig. Find NJ.com on Facebook.