Schaff, Philip. "Prayer and Fasting." The Oldest Church Manual Called the Teaching of the Twelve Apostles. Second Edition, Revised and Enlarged. New York: Funk & Wagnalls, 1886, 29.
Schaff interprets the recitation of the Lord's Prayer from the Didache as following the Jewish custom of prayers at 9:00, 12:00, and 3:00. The addition of dawn and dusk he attributes to Tertullian (Schaff 1886, 29).
The wording of the Lord's Prayer has only slight differences from the version in Matthew's Gospel. The doxology at the end is not found in Matthew but appears in similar form in Jewish customs.
Schaff considers that the instruction about fasting "goes beyond the New Testament and interferes with evangelical freedom" (Schaff 1886, 29). Jesus condemned hypocrisy in the Pharisees and did not command particular days for fasting.