A.T. Robertson Commentary John 1:27

"[even] he that cometh after me, the latchet of whose shoe I am not worthy to unloose." — John 1:27 (ASV)

Coming after me (οπισω μου ερχομενος). No article (ο) in Aleph B. John as the forerunner of the Messiah has preceded him in time, but not in rank as he instantly adds.

The latchet of whose shoe I am not worthy to unloose (ου ουκ ειμ αξιος ινα λυσω αυτου τον ιμαντα του υποδηματος). Literally, "of whom I am not worthy that I unloose the latchet (see Mr 1:7 for ιμας) of his sandal (see Mt 3:11 for υποδημα, bound under the foot)." Only use of αξιος with ινα in John, though used by Paul in this saying of the Baptist (Acts 13:25), ικανος ινα in Mt 3:8, but ικανος λυσα (aorist active infinitive instead of λυσω, aorist active subjunctive) in Mr 1:7 (Luke 3:16) and βαστασα in Mt 3:11.