Matthew's Gospel (AD 80-100) shows knowledge of the Didache's first three layers.

Luke's Gospel (AD 70-100) shows knowledge of the Didache's oldest layer.

Mark's Gospel (c. AD 69) shows knowledge of the Didache's oldest layer.

1 Corinthians (c. AD 55) shows knowledge of the Didache's oldest layer.

1 Thessalonians (c. AD 50) shows knowledge of the Didache's oldest layer.

If the base layer of the Didache predates 1 Thessalonians and was communicated to the Thessalonian converts by Paul, Silvanus and Timothy during the founding mission, then the possibility arises that it is somehow related to the so-called Apostolic Decree of c. AD 49, the first Christian document.