9 Over this mighty multitude God has Himself set rulers with power to govern, and He has willed that one should be the head of all, and the chief and unerring teacher of truth, to whom He has given "the keys of the kingdom of heaven."(9) "Feed My lambs, feed My sheep."(10) "I have prayed for thee that thy faith fail not."(11)
Source: Immortale Dei (Vatican.va)