One of the refugees Pope Francis met on Lesbos was the Muslim widower of a Syrian Christian woman killed for her faith, reports the Associated Press.
The women was killed by extremists when she refused to renounce her faith, Francis said.
The Pope departed from his prepared text during his address earlier today in St Peter's Square.
He said that among the 300 refugees he met yesterday in the refugee camp on Lesbos was a widower with two children.
Francis said: "He is Muslim, and he told me that he married a Christian girl. They loved each other and respected each other. But unfortunately the young woman's throat was slashed by terrorists because she didn't want to deny Christ and abandon her faith."
He added: "She is a martyr!" and said the widower had wept as he told the story.
Adults and children broke down in tears before the head of the Roman Catholic church during his visit.
While borders have now largely been shut for migrants, Francis symbolically took a small group of refugees with him on his aircraft as he left the island after a five-hour visit.
"The Pope has desired to make a gesture of welcome regarding refugees, accompanying on his plane to Rome three families of refugees from Syria, 12 people in all, including six children," a statement issued by the Vatican said.
The individuals were selected from lots drawn, media reports said. They had been in camps before a deal between the EU and Turkey came into effect to halt the migrant flow on March 20.
Sant'Egidio, a Christian community which offers help for those in need and headquartered in Rome, will be looking after the families.
