Gregory the Great — on Ezek 3:16 (Homilies on Ezekiel, Book 1, Homily 11)

“In that he sat mourning for seven days, and after the seventh day received the words of the Lord's command that he ought to speak, he clearly indicates that during those same days he had been silent while mourning. Now he had been sent to preach, and yet sitting for seven days he was silent. What is it that the holy prophet suggests to us in this silence of his, except that he truly knows how to speak who has first learned how to be silent well? For the discipline of silence is, as it were, a kind of nourishment for speech. And rightly does he receive the gift of speaking through increasing grace, who first keeps silent in an orderly manner through humility. Hence it is said through Solomon: "A time to be silent, and a time to speak." For he did not say, "A time to speak, and a time to be silent," but he puts the time for silence first, and afterwards adds that for speaking, because we ought to learn to speak not by speaking but by being silent. If therefore the holy prophet who had been sent to speak was first silent for a long time, so that afterwards he might speak rightly, we must consider how great a fault it is for him not to be silent whom no necessity compels to speak.”