Annual fast on the Day of Atonement (Lv. 16:29, 31; 23:27–32; Nu. 29:7). Even called “the Fast” in Acts 27:9.
Occasional fasts were personal (Hannah 1 Sam 1:7; David 2 Sam. 12:22) or corporate (Jdg. 20:26; Joel 1:14).
Fasting for others like praying for others (e.g., Ester 4:15–17 asks people to fast for her before she risks her life by approaching the king).
Anna fasted (Luke 2:37)
Jesus says that his disciples will fast (Matt. 6:16–18; 9:14–17).
The apostles and first Christians fast (Acts 13:2–3, 14:23)
SC: “Fasting and bodily preparation are certainly fine outward training.”
We believe that God’s glory and command require penitence to produce good fruits, and that good fruits like true fasting, prayer, and charity have his command. AP XII:129
Luther (AE 76:360): “No one should despise or ignore fasting, wakefulness, and labor just because no one is made godly through them. Even though you do not become godly through them, you should still use them, and not give free reign to the flesh and become lazy.”
Luther (AE 76:366): Two kinds of good fasting, willing and by necessity (but still willing to endure it). The second happens with greater faith because we do not control it. Christ’s fasting was of the second kind (“driven by the Spirit into the wilderness”).
Urbanus Rhegius, Preaching the Reformation, 81–5: He approves of the Lenten fast. Two kinds of fasting, general moderation of Christian living; special fasts like Lent. How lazy we are compared to the early Christians.
Conrad Dietrich, Institutiones Catecheticae, 403: “For fasting, according to the standing linguistic usage of Scripture and the custom of the saints of the Old as well as of the New Testament means literally: to abstain from all nourishment, whether it lasts for a day, as the people of God generally practiced it (Num. 29:7; Judges 20:26; 2 Sam. 1:12; 3:35, etc.) or for several days, (two days, Neh. 1:4; or three, Esther 4:6; or even four, Acts 10:30). In a non-literal sense it is called fasting when one lives off of scanty and meager fare and at least takes to himself no breakfast or no lunch, and also consumes cheaper and rougher food and drink for a long period of time (see 1 Sam. 31:13; Dan. 10:3).”
Todd Peperkorn on Matthew 6 and prayer, fasting, and almsgiving: “Jesus exhorts us not to do these things as a show. There is no room in the Christian faith for works righteousness. But Jesus does assume that the Christian will be doing these things. In my experience, the greatest danger today lies in rejecting these ancient practices of prayer, fasting and almsgiving, because I think I know better than thousands of years of Christian and pre-Christian history. American culture is much more inclined to overindulgence and entitlement than we are to works righteousness. At the risk of being labeled a “closet catholic,” I’m going to go out on a limb and say that for most of us, we could use a little less indulgence, and a little more discipline in our lives.”
TLSB, “When You Fast,” p. 189.