During his in-flight press conference, the pope also spoke about his health, youth suicide, and access to the sacraments.
Pope Emeritus Benedict XVI was laid to rest Thursday following a funeral Mass attended by tens of thousands of people.
For centuries, the rosary has been considered a weapon of protection against evil and a powerful tool of intercession.
The feast of Saint Peter and Saint Paul, whose official name is the joint Solemnity of Saints Peter and Paul, is the commemoration of the martyrdom in Rome of the apostles Simon Peter and Paul of Tarsus, celebrated on June 29.