Shamsi Ali, the imam the Jamaica Muslim Center in Queens
© Credit George Etheredge/The New York TimesShamsi Ali, the imam the Jamaica Muslim Center in Queens, said he planned to invite non-Muslims to attend his mosque’s services on Eid al-Adha to learn about the holiday and Islam.
Every year, Muslim leaders around the world look to the moon to predict the date for one of their most important holidays, Eid al-Adha — the feast of sacrifice.

When Habeeb Ahmed began about two months ago to plan for that holy day, he noticed a potentially fraught coincidence: Eid al-Adha could fall on Sept. 11.

"Some people might want to make something out of that," said Mr. Ahmed, who was recently elected president of the Islamic Center of Long Island, adding that he could easily foresee how some might misunderstand the festivities, and say, "Look at these Muslims, they are celebrating 9/11."

The potential for the holiday to fall on the 15th anniversary of the terrorist attacks has stirred apprehension among Muslims in New York City and across the country at a time when violent acts committed by religious extremists have provoked inflammatory political rhetoric and helped fuel a surge in hate crimes against Muslims.

In New York, the possibility of the holiday falling on Sept. 11 has intensified security concerns and fears already reverberating throughout the Muslim community after the killings of an imam and his assistant in Queens this month. For some, it also resurfaces memories of the backlash and the police surveillance directed at Muslims in the years after the attacks.

"Our community is like, 'What are we supposed to do?'" Linda Sarsour, the executive director of the Arab American Association of New York, said. She said she had sat through extensive meetings with other leaders grappling with the possibility and how best to prepare for it.

"I should not have to think about that," Ms. Sarsour said. "What am I supposed to tell my kids?"

Eid al-Adha honors the willingness of Ibrahim, or Abraham, to sacrifice his son Ishmael as an act of submission to God's command. The holy day can also serve as an opportunity to honor the sacrifice of those who were killed on Sept. 11, 2001, said Abdul Bhuiyan, the secretary-general of the Majlis Ashura, the Islamic Leadership Council of New York.

"It's a day of remembrance and observance," Mr. Bhuiyan said.

The likelihood of this year's Eid al-Adha landing on Sept. 11 is still unclear. Every year, the holiday takes place 10 days after the sighting of a new moon at the start of the month of Dhu al-Hijjah, according to the Islamic calendar. Exactly when the month begins depends on when a new moon is spotted, and the month is expected to start this year on Sept. 1 or 2.

In the past, another major Muslim holiday, Eid al-Fitr, has fallen near Sept. 11, but neither holiday has yet to actually coincide with the date.

"It's on the minds of every Muslim leader in the country right now," Robert McCaw, the director of government affairs at the Council on American-Islamic Relations, said. "We grieved like everyone else," he added, referring to the Sept. 11 attacks. "We remember this day not because we're Muslim, but because we're American."

Tahir Kukiqi, the imam at the Albanian Islamic Cultural Center on Staten Island
© George Etheredge/The New York TimesTahir Kukiqi, the imam at the Albanian Islamic Cultural Center on Staten Island, said this year’s holiday would be more somber than in the past. “We will be praying for the well-being of our country,” he said.
Nevertheless, local and national Muslim officials have urged imams and other leaders to talk to the authorities to ensure that security is in place for the holiday, Mr. Bhuiyan said. In New York City, the police have already been providing additional security at many mosques since the killings in Queens.

The possibility that the holiday could fall on Sept. 11 has prompted some mosques that frequently hold holy day services outdoors, such as Masjid Hamza in Valley Stream, N.Y., on Long Island, to move their prayer services inside to avoid congregating in a public place.

Karim Mozawalla, a trustee at Masjid Hamza, said that in some past years, its members had gathered in a public park for a prayer service. This year, multiple smaller prayer services will be held inside the mosque.

Oussama Jammal, the secretary general of the United States Council of Muslim Organizations, said the group planned to start a national Muslim voter registration drive on the holiday, in part as an opportunity to reach large crowds of Muslims.

Tahir Kukiqi, the imam at the Albanian Islamic Cultural Center on Staten Island, said the concerns about a potential backlash around the holiday resonated on a personal level: In June, a man entered Mr. Kukiqi's mosque shouting expletives and yelling, "I am going to kill you" and "You are here to conquer us."

The man grabbed a pipe from the wall and threatened the imam. As Mr. Kukiqi called 911, the man dropped the pipe and ran away. A suspect was later arrested and faced hate crime charges.

"There is a lot of hate out there," Mr. Kukiqi said. "And there is a lot of ignorance as well."

This year's Eid al-Adha sermon, he said, will be more somber than in previous years.

"We will be praying for their souls," he said, referring to the Sept. 11 victims. "We will be praying for the well-being of our country."

In Dearborn, Mich., home to one of the country's largest concentrations of Arab-Americans, Ibrahim Kazerooni, the imam at the Islamic Center of America, said Muslims should celebrate as they normally would, attending prayer services, donating meat or money to the poor and sharing a meal with family and friends.

As for the date, he said, "We need to be mindful of it, but at the same time not be overburdened to the degree that it paralyzes the community."

Shamsi Ali, the imam at the Jamaica Muslim Center in Queens, said his congregation still intended to host its outdoor prayer service, which is expected to attract 20,000 people, one of the largest gatherings in New York City.

Mr. Ali, along with several other imams in the city, plans to invite non-Muslim neighbors and religious leaders to attend services and learn about the significance of the holiday, while also praying for the Sept. 11 victims.

"If people are trying to build walls, we are building bridges," Mr. Ali said. "That's really what New York is all about."