Sirach 6:16
Ben Sira, Ecclesiasticus14 Faithful friends are a sturdy shelter: whoever finds one has found a treasure. 15 Faithful friends are beyond price; no amount can balance their worth. 16 Faithful friends are a bag of life*; and those who fear the Lord will find them. 17 Those who fear the Lord direct their friendship aright, for as they are, so are their neighbors also. 18 My child, from your youth choose discipline, and when you have gray hair you will still find wisdom.
Ambrose On the Duty of the Clergy 3.22
128 Open your breast to a friend that he may be faithful to you, and that you may receive from him the delight of your life. For a faithful friend is the medicine of life and the grace of immortality. Give way to a friend as to an equal, and be not ashamed to be beforehand with your friend in doing kindly duties. For friendship knows nothing of pride. So the wise man says: Do not blush to greet a friend. Do not desert a friend in time of need, nor forsake him nor fail him, for friendship is the support of life. Let us then bear our burdens as the Apostle has taught: for he spoke to those whom the charity of the same one body had embraced together. If friends in prosperity help friends, why do they not also in times of adversity offer their support? Let us aid by giving counsel, let us offer our best endeavours, let us sympathize with them with all our heart.
Notes and References
"... As a second example of reception history, we can consider another oft-cited Sirach passage, the first poem on friendship (Sirach 6:5–17). Within Jewish tradition, the Babylonian Talmud cites a form of the admonition in Sirach 6:6: “Let those who seek your peace be many; reveal your confidence to one in a thousand” (b. Sanhedrin 100b). Several references to Sirach 6:5–17 occur within Christian literature from the late fourth century. Testimony to the friendship existing among the Cappadocian Fathers is evident in the oration, pronounced in 372 by Gregory of Nazianzus (d. 389), shortly after he was made bishop, in the presence of his two friends, Gregory of Nyssa and his brother Basil of Caesarea. Acknowledging the value of their friendship, the oration refers to Sirach 6:14–15 (Or. 11). Around the same time, Ambrose of Milan (d. 397), twice quotes Sirach 6:16, in association with other verses of Sirach on friendship, in its expanded Latin form: “A faithful friend is a medicine of life and immortality” (Off. 2:7 [37]). Another contemporary bishop, John Chrysostom (d. 407), refers to Sirach 6:14–16 to explain the extent of true friendship (Hom. 1 Thess.), while commenting on Paul’s tender treatment of his converts in Thessalonica (1 Thessalonians 2:7–8) ..."
Corley, Jeremy "Sirach" in Oegema, Gerbern S. (ed.) The Oxford Handbook of the Apocrypha (pp. 284-305) Oxford University Press, 2021