Matt 6:4 αυτος

About a quarter of the Greek manuscript tradition omits the pronoun αυτος before the verb αποδωσει (cf. ℵ B L U Z Θ 047 0250 f13 33 892 1424 [+355 mss] lat sy-s.c; Or), but most witnesses retain it in that position (cf. D E K M S W Δ Π Σ Φ Ω 055 0211 0257 f1 [+1130 mss] h q sy-p.h) and ten place it after σοι. Metzger (12) calls the reading an obvious expansion designed "to heighten the impressiveness of the saying," but this simplistic explanation is not critically sound. From all we know about the early period, it was not addition but omission, especially of single words and particles, that was the predominating characteristic of scribal error (see note on Matt 1:22 του and the literature cited there).
     Briefly, Matthäi (84) notes, "It could be left out and was therefore omitted." Likewise, Kühnöl (175) writes: "Wrongly did Fritzsche and Lachmann judge that αυτος should be expunged, for scribes omitted this pronoun because to them it appeared superfluous." Griesbach (1:64) also judges that αυτος "was omitted in some [manuscripts], either by the negligence of scribes (for it can be left out without harming the sense) or even for this reason, that in verses 6 and 18 the same sentence is repeated without αυτος. . . . Certainly it should be judged that the versions and fathers that do not mention the pronoun do not have as much weight in this kind of reading as they do elsewhere."
     Bloomfield (GNT, 1:42) mentions a few examples where αυτος is used either to take up again the subject or object of the verb (Matt 12:50; Mark 3:35; John 7:4; 14:10; 1 Cor 7:13) or as emphatic (John 1:27; 7:4), where "Classic propriety would require ουτος."
     The various reasons why αυτος came to be omitted, then, are: (1) accident, especially facilitated by homoeoarchton error (α...α); (2) editorial pruning of what was deemed superfluous; (3) conformation to the saying in 6:6, 18 where the word is absent; (4) removal of what could have been deemed unclassical.
     Additionally, a structural reason for including αυτος here but not in verses 6 and 18 may be in view. Matthew is known elsewhere in the Sermon on the Mount to repeat similar phrases first in a fuller form and later in an abbreviated form. See, for example, the structural technique as found in most manuscripts (including NA27):

Matt 5:21: ηκουσατε οτι ερρεθη τοις αρχαιοις
Matt 5:27: ηκουσατε οτι ερρεθη
Matt 5:31: ερρεθη δε

Compare the above structural technique with the following according to most manuscripts:

Matt 6:4: αυτος αποδωσει σοι εν τω φανερω
Matt 6:6: αποδωσει σοι εν τω φανερω
Matt 6:18: αποδωσει σοι

Such stands in striking contrast to the harmonized and thus generally less praiseworthy form that appears in NA27:

Matt 6:4: αποδωσει σοι
Matt 6:6: αποδωσει σοι
Matt 6:18: αποδωσει σοι

For complete manuscript data on αυτος at this place, see the following post on Matt 6:4 εν τω φανερω.