Comment by rietta

It was certainly popular enough to be included in the 4th-century Codex Sinaiticus, which is the oldest extant "complete" Bible (Genesis through Revelation) in a single bound volume. Interestingly, in that manuscript, The Shepherd of Hermas and the Epistle of Barnabas actually appear right after the New Testament. The library has published scanned copies online at https://www.codexsinaiticus.org/en/. It is an epic resource for anyone studying this history or textual criticism.