"You must understand. We are not people of bombs and guns," he explained. "But when someone insults our Prophet, we cannot bear it. It is a matter of inexpressible emotions."
The idolisation of Qadri - a martyr to some Pakistani Muslims and a murderer to others - stems from his confession that he killed out of religious duty.
Qadri believed that his boss, Punjab Governor Salman Taseer, had committed blasphemy by calling for reforms in Pakistan's draconian laws against insulting Islam or the Prophet Muhammad. Taseer had especially spoken out in defence of a Christian peasant woman, Asia Bibi, who was sent to prison for blasphemy.
Yesterday, police secured much of the capital in an effort to prevent Qadri's supporters from interfering with the regional summit. Most major streets were blocked off, and schools and government offices were closed after noon.
Qadri devotees had planned to rally in a park in Rawalpindi City and make their way to the shrine 32km away, but the park area was sealed off and only a few thousand people managed to reach Barakaho.
Authorities prevented any physical confrontation, but the coinciding economic and religious events seemed an especially stark illustration of the deep divide confronting Pakistan as its leaders struggle between contradictory pulls towards global outreach and political modernisation, on the one hand, and religious fervour and radicalisation on the other.
Abroad, Pakistan's Government is often criticized for sheltering Islamist militias that attack Afghanistan and India, but at home its leaders must contend with the intense devotion of its Sunni-majority population, whose historically moderate views have become increasingly hard-line under the influence of fundamentalist clerics and teachings.
Authorities have periodically cracked down on violent Islamist groups, usually after high-profile attacks such as the 2014 massacre that killed 141 students and teachers at an army school and the spate of deadly suicide bombings last month, including one in a crowded plaza in Lahore city and another at a famous Sufi shrine in rural Sindh province. The recent attacks prompted a nationwide anti-terrorism campaign by the army and the police.
But when it comes to sensitive matters of faith, especially blasphemy, the state has largely given in to the hard-liners. Under Pakistan's harsh blasphemy laws, any perceived offence against the Prophet Muhammad or Islam - even a dropped Koran or a mild curse - can be punishable by death. Vigilante mobs often take matters into their own hands, and false blasphemy charges are often hurled at personal enemies or members of religious minorities.
Members of parliament have repeatedly proposed amendments to moderate the blasphemy laws, but they have always been quashed amid strong opposition by religious party leaders. The state eventually convicted and executed Qadri, but it allowed thousands of devotees to parade his coffin aloft through the streets of Rawalpindi city, reinforcing his growing stature as a cult figure.
"This is a visible sign of growing extremism in our society. If we eulogise the killers of innocent people, we wonder in what direction this country is going," said Asma Jehangir, a leading human rights activist.
"If these followers of Qadri call themselves peaceful, it is a blatant lie. There is no difference between them and the Taliban," she added. "If the state doesn't stop them, more and more people will take the law into their own hands and turn into heroes."
At the green-domed hillside shrine to Qadri, officials kept order among several thousand devotees and screened everyone with metal detectors. Many of his relatives were there, including his widow and 5-year-old son.
His elder brother Malik Qadri, a telecommunications technician, stressed that their religious movement, "Invitation to Islam," opposes violence. He said that the Government had executed Qadri because of "foreign pressure," but that even his widow was "happy because he gave his life to protect the Prophet."
Some speakers at the gathering, however, seemed to exult in the violent example Qadri had set and the renown his crime had brought. Among them was Allama Hanif Qureshi, a leader of the Barelvi sect of Sunni Islam.
"Today there are millions of Qadri lovers, and there are many children named after Qadri, but there are none named after Salman Taseer or the apostate Asia Bibi," Qureshi said. "The government tried to stop the people from participating in this gathering, but they cannot stop us forever. We will continue with his mission. We will not spare blasphemers."
The adoration of Qadri has been a factor in the growing rivalry between the relatively mainstream Barelvis, who oppose the Taliban and other armed militias, and the more radical Deobandi sect, which has spawned many such religious warriors. With more than 175 million Sunni Muslims in Pakistan, the competition for support is fierce, and Qadri's martyrdom has become a huge draw for the faithful.
