Ambrose of Milan

Blessed is that servant [Paul] who can say: "I have fed you with milk and not with meat; for until now you were not able to bear it." … Yet he—being so great a man and chosen by Christ for the care of his flock in order to strengthen the weak and to heal the sick—rejects immediately after a single admonition a heretic from the fold entrusted to him. This he does for fear that the taint of one erring sheep might infect the whole flock with a spreading sore. He further bids that foolish questions and contentions be avoided.