The blast targeted the gates of the Eidgah Mosque in the Afghan capital, where a funeral service was being held for the mother of Taliban spokesman Zabihullah Muhajid, who tweeted that the blast had claimed the lives of civilians.
It was not immediately clear how many people were killed or injured in the attack.
Reports on social media described a large detonation and emergency services rushing to the scene.
No one has claimed responsibility for the bombing.
A little more than a month since insurgents seized control of Afghanistan, taking control of major cities and installing themselves in the presidential palace in Kabul, the Taliban’s new interim government is facing a range of threats from internal enemies.