Video of the attack shows the northern Afghan militia commander approaching thousands of worshippers who had gathered outside the mosque.
As a crowd of supporters from the front rows rushed toward Dostum, bodyguards formed a circle around him. The suicide bomber managed to get within 10 meters of Dostum before he was stopped by the guards.
It was then that he detonated a belt of explosives hidden beneath his clothing.
The video shows a small gray cloud of smoke rising just meters from Dostum at the moment of the blast. The bodies of his guards and supporters protected Dostum from shrapnel.
The crowd dispersed quickly, revealing the body of the young, bearded suicide bomber.
RFE/RL's correspondent in Shiberghan spoke to one of Dostum's supporters, who sustained a shrapnel injury because, he said, he rushed between Dostum and the bomber.
"I was just four or five meters away from the blast, and I heard the sound," the man said. "But I couldn't see anything [because of all the people crowded together]. It wasn't until later that I realized I had sustained minor injuries."
Haroon Arif, a doctor at the main hospital in Shiberghan, told RFE/RL that more than 20 people injured by the blast were brought to his facility. He said it is unclear whether the most seriously injured will survive.
"Five of them were seriously injured, and they are in our emergency operation room," Arif said. "Our surgeons are working to save these people. Besides the suicide bomber himself, nobody else was killed."
The general's brother, Qadir Dostum, was among those who sustained minor injuries. He told Reuters he was embracing his brother at the moment of the explosion and was struck in the face by shrapnel.
Ehsan Zari, an aide to Dostum, said it is too early to say who carried out the attack or what impact it might have on relations with rival militia factions.
Another aide said Dostum spoke by telephone with his chief rival in the north -- ethnic Tajik commander Mohammad Atta -- after the attack.
As a key factional leader in the former United Front (aka Northern Alliance), Dostum worked closely with U.S. Special Forces in the campaign to oust the Taliban after the 11 September 2001 terrorist attacks in the United States.
Dostum was deputy defense minister in Afghan President Hamid Karzai's transitional government. He ran unsuccessfully in October's presidential election, which was won by Karzai, and was left out of Karzai's new cabinet.
(from RFE/RL's Afghan Service and agency reports)