VII.xxxv.2. Blessed Antony was accustomed to say, “The ancient fathers went into the desert, and having been healed became healers. They then came back and healed others. There are those among us nowadays who go into the desert and try to heal others without first being healed, and thus do weaknesses come back among us and our last state is worse than the first. For this reason it was said to us, ‘Physician first heal thyself'” (Luke 4:23).
De Vitis Patrum, Book 7, chapter 35.