They test their devotion by performing physical endurance tests and pierce parts of their bodies with knives and skewers.
The Islamic order, Tariqah Al Kasnazaniyah, embraces Sufi traditions, which is a mystical Islamic belief.
It is practiced by some Muslims who seek religious truth and show devotion by performing unimaginable feats of endurance.
The ceremony starts with men, many with long hair, standing is rows reciting religious prayers and swaying in devotion to god - traditional drums add to their vocal rhythm.
The Tariqah Al Kasnazaniyah claim their lineage through Prophet Mohammed, via his son-in-law Ali bin Talib.
The word 'Aliyyah' is also derived from his name.
This style of Sufisim is also practiced in Iran and Turkey and claims it makes no distinction between Shia and Sunni Muslims, or Kurdish or Arab followers.
It was because of this that they were banned under Islamic State (ISIS) in Mosul between 2014 and 2017 and many of their followers had to escape the city.
The 'Dhikr' ceremony (remembrance of Allah) that they are performing now had to be abandoned.
It restarted when Mosul was liberated from ISIS and Tariqah Al Kasnazaniyah followers returned and started their practices without fear of persecution.
"We and Daesh (ISIS) are opposites, because Daesh is promoting terrorism, while we are calling for peace," says Tariq Sheet Mahmoud, a Sufi Khalifa.
"Also, the Sufi path is against the Takfiri path (declaring dissenters to not be true Muslims). Therefore we were wanted by Daesh, because Daesh make no exceptions for anyone, apart from their followers."
The men, young and old, involved in the ceremony follow the lead of one spiritual leader who recites religious verses.
To show his devotion, one man allows the khalifa to hammer knives in his head without showing any fear.
Another shows endurance by having a metal skewer pierced through his cheek.
The knives and the skewers are later removed and the men appear unharmed.
During the religious singing one man hammers a knife in his eye socket and retracts it without a drop of blood or any damage to his eye.
Mystical sufism has deep roots in the Iraqi society, and has many followers from all the different ethnic and religious groups.
Sufism followers formed many insurgent groups to fight the coalition forces in Iraq after the war in 2003.
They include the The Men of the Army of al-Naqshbandia Order, who participated in the battle of Fallujah against the American troops in 2006.
However, Sufism has been targeted recently, very often by Muslim extremists.
An example was the deadly militant attack on a Sufi mosque in Sinai peninsula in Egypt, which killed at least 305 people in 2017.
This was described by the officials as "the worst terrorist attack in Egypt's modern history."
