Evangelii Praecones §13

¹³ Missionaries in foreign lands who die in the fulfilment of their sacred duty are seeds destined, when God so wills, to bear abundant fruit. Wherefore the Apostle Paul asserted: "We glory in tribulations." St. Cyprian, Bishop and Martyr, consoled and animated the Christians of his day with these words: "The Lord has willed that we should even rejoice over persecutions because, when persecutions occur, then the faith is crowned, God's soldiers are put to the test, and heaven is opened to martyrs. We have not enlisted in an army merely to think of peace and to decline battle, seeing that the Lord, the master of humility, tolerance and suffering, has taken the first place in the conflict, that He might first do what He taught us to do and that He might Himself first endure for us what He exhorts us to endure."