From Imitation of Christ by Thomas à Kempis:
[Note from Encyclopedia Britannica: “Thomas À Kempis, original name Thomas Hemerken, (born 1379/80, Kempen, near Düsseldorf, Germany—died Aug. 8, 1471, Bishopric of Utrecht, Netherlands), Christian theologian, the [recognized] author of Imitatio Christi (Imitation of Christ), a devotional book that, with the exception of the Bible, has been considered the most influential work in Christian literature.”]
“Do not open your heart to every man, but discuss your affairs with one who is wise and who fears God. Do not fawn upon the rich, and do not be fond of mingling with the great. Associate with the humble and the simple, with the devout and virtuous, and with them speak of edifying things. Seek only the intimacy of God and of His angels, and avoid the notice of men.
Shun the gossip of men as much as possible, for discussion of worldly affairs, even though sincere, is a great distraction inasmuch as we are quickly ensnared and captivated by vanity.
Many a time I wish that I had held my peace and had not associated with men. Why, indeed, do we converse and gossip among ourselves when we so seldom part without a troubled conscience? We do so because we seek comfort from one another’s conversation and wish to ease the mind wearied by diverse thoughts. Hence, we talk and think quite fondly of things we like very much or of things we dislike intensely. But, sad to say, we often talk vainly and to no purpose; for this external pleasure effectively bars inward and divine consolation.
Therefore we must watch and pray lest time pass idly.
When the right and opportune moment comes for speaking, say something that will edify.
Bad habits and indifference to spiritual progress do much to remove the guard from the tongue. Devout conversation on spiritual matters, on the contrary, is a great aid to spiritual progress, especially when persons of the same mind and spirit associate together in God.”
[resources: Imitation of Christ]