During the holy month of Ramadan, Muslims fast daily between dawn and sunset and the break-the-fast dinner, called the iftar, is traditionally a festive and spiritual event.
U.S. President Barack Obama hosts an iftar annually at the White House. But Harper's office says Monday is the first time one has been held at 24 Sussex.
In his speech to the dinner, Harper says his house ultimately belongs to all Canadians and hopes everyone can share in the blessings of the month.
He also notes tradition is that those who host an iftar bring goodness upon themselves.
The Conservative government's relationship with the Muslim community has been tense, with major flare-ups over issues such as a new bill banning face veils during citizenship ceremonies.
Harper has also been criticized for focusing more on radical elements within Islam than on reaching out to mainstream Muslims in the aftermath of terrorist attacks linked to radicalization.
But in his speech Monday, he paid tribute to the contributions of the community.
"Like so many others, the followers of Islam have, overwhelmingly, come to Canada, seeking freedom, opportunity and tolerance," he said, according to a prepared text of his remarks.
Among those at the dinner was Sen. Salma Ataullahjan, who is a Sunni Muslim.
The prime minister's office didn't immediately release a list of those who attended.
"This house belongs ultimately to all Canadians," Harper said.
"And I hope all Canadians, especially our Muslim friends and neighbours, share in these blessings tonight."
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