St. Faustina
“The Holy Spirit does not speak to a soul that is distracted and garrulous. He speaks by His quiet inspirations to a soul that is recollected, to a soul that knows how to keep silence. If silence were strictly observed, there would not be any grumbling, bitterness, slandering, or gossip, and charity would not be tarnished. In a word, many wrongs would not be done. Silent lips are pure gold and bear witness to holiness within.”
Source: St. Faustina, Diary: Divine Mercy in My Soul