Jump To ECM Entry Online Commentary Introduction
The case is very similar to 7:7/12. Here, fluctuation between the forms could be expected to be more vivid because they are phonetically identical, but incoherencies only occur in the b attestation.
 Pervo (225) and Barrett (428) agree that the hybrid construction of ἐὰν μή + fut. would not reflect the author’s style. The decisive argument for a, however, is the coherent majority attestation spanning from the earliest to the latest witnesses.