The bomber joined the ceremony in Potiskum, Yobe State and blew himself up, witnesses said.
Premium Times quote a resident of the town, Adamu Mohammed, as saying “My sister lost three of her sons in the blast,”
No group has said it carried out the attack, but suspicion is bound to fall on militant Sunni Islamist group Boko Haram.
It denounces Shiites, a small minority in Nigeria, as non-Muslims.
Witnesses said the bomb exploded as the crowd was marking Ashura, a solemn day when Shiites mourn the martyrdom of Hussein, a grandson of the Prophet Muhammad, in 680 AD at Karbala in modern-day Iraq.