Mustafa and Zejneba Hardaga welcomed the Kavilio family, Jewish refugees who had escaped Sarajevo, when the Germans invaded in 1941. The Hardagas were a traditional Muslim family, and despite their custom for women to cover their faces in front of strangers, the Hardaga women were not obliged to cover their faces in the presence of the Kavilios. They were greeted as family in the Hardaga home.

The Kavilios stayed with the Hardagas for a short while until Josef Kavilio was able to move his wife and children to a safer area under Italian rule. Kavilio himself stayed behind to liquidate his business, but eventually was arrested, imprisoned, and forced into slave labour. Zejneba Hardaga, the wife of Mustafa, who discovered where Kavilio was working, would regularly bring food to the prisoners. Josef Kavilio eventually escaped and returned to the Hardaga home. Though the Kavilio family had to flee yet again before the war ended, they eventually reunited and returned to Sarajevo in 1945, staying with the Hardagas until they could find a place of their own. The Hardagas continuously risked their own lives to save this family that they considered their own.