Matt 7:21 ουρανοις

Some early manuscripts (ℵ B C Z Δ Θ 0281vid f1 33. 892. 1424) and most editors (Bover, Greeven, Lachmann, Merk, Soden, Tischendorf [8th], Vogels) naturally add τοις before ουρανοις, but authorial usage indicates that after this particular construction with the genitive, the anathrous ουρανοις (without the article) is to be preferred, as evidenced by most pre-10th-century witnesses (E G K L M O S U V W X Δ Π Σ Φ Ω 047 Byz f13.35 565. 1500. 2224) and Tischendorf (7th). In considering Matthew's style for the construction πατηρ + PRONOUN + ARTICLE + εν +/- ARTICLE + ουρανοις, only the indisputable passages are considered (i.e., where the Nestle-Aland and Robinson-Pierpont editions agree), laying aside temporarily the four disputable passages (i.e., 5:45; 7:21; 10:32, 33). What is discovered is that the article always precedes ουρανοις except when πατηρ and its accompanying articles are in the genitive case:

nominative/vocative:
ο πατηρ υμων ο εν τοις ουρανοις/ο ουρανιος (5:48; 7:11)
Πατερ ημων ο εν τοις ουρανοις (6:9)
ο πατηρ μου ο εν τοις ουρανοις (16:17)
[ο πατηρ υμων/μου ο ουρανιος (6:14, 26, 32; 15:13; 18:35)]

dative:
τω πατρι υμων τω εν τοις ουρανοις (6:1)
τω πατρι σου τω εν τω κρυπτω (6:6, 18)

accusative:
τον πατερα υμων τον εν τοις ουρανοις (5:16)

BUT:

genitive:
του πατρος μου του εν ουρανοις (12:50; 18:10, 19)
του πατρος υμων του εν ουρανοις (18:14)

     Allowing Matthew's indisputable custom to inform the disputable cases leads to the probability that in those three passages where after the genitive construction (i.e., after του πατρος ... του εν ...) a minority of witnesses adds the article before ουρανοις (i.e. Matt 7:21; 10:32, 33), the addition should be considered secondary. Likewise in Matt 5:45 τοις, where a divided majority of witnesses adds the article after the same construction, the addition of τοις is likely secondary. In all four of these variations, the addition of the article may be seen as assimilation to the pattern following the constructions with all of the other cases, i.e., after the nominative, dative, accusative, and vocative constructions. Moreover, preference for assimilation as the likeliest cause of the addition of τοις in the present case is increased due to the presence of τοις in every preceding such construction in Matthew up to this point (5:16, 48; 6:1, 6, 9, 18; 7:11), with the nearest such occurrence just 10 verses earlier (7:11). See the note on Matt 5:45 τοις for an initial discussion of the textual problem.

Matt 7:16 σταφυλην

Although the plural σταφυλας is present in a few mostly-related witnesses predating the 10th century (ℵ B C1 0281 f1 892 lat sy-h co) and followed by Bover, Greeven, Lachmann, Merk, Soden, and Tischendorf (8th), there are several reasons why the plural appears to be a secondary correction for the singular σταφυλην, which appears in all the other early witnesses (C*.2 E G K L M O S U V W X Δ Θ Π Σ Φ Ω 047 0211 Byz f13.35 565. 1424. 1500. 2224) and is followed by Vogels and Tischendorf (7th). First, the wording of the parallel in Luke 6:44b is so different that supposed harmonization in so many diverse witnesses to the singular form there is unlikely. Compare:

Matt 7:16b: μήτι συλλέγουσιν ἀπὸ ἀκανθῶν [σταφυλὰς/σταφυλὴν] ἢ ἀπὸ τριβόλων σῦκα;
Luke 6:44b: οὐ γὰρ ἐξ ἀκανθῶν συλλέγουσιν σῦκα, οὐδὲ ἐκ βάτου σταφυλὴν τρυγῶσιν.

Second, as Meyer (161) notes, the plural naturally could have originated in consequence of the plural συλλεγουσιν and especially in conformation to the plural συκα in the coordinate clause. Third, facilitating the alteration just mentioned are transcriptional considerations, which favor a possible original loss of the singular ending -ην in an early Egyptian archetype due to homoeoteleuton error from the particle η that follows (η...η). Finally, a few witnesses (L Ψ f13 it-c.e sy co go) make the same alteration (i.e., σταφυλας for σταφυλην) in Luke 6:44, an indication that the tendency of the alteration was not isolated, especially in the versions, where in an early diglot the chance of the plural form passing from a vernacular version into the Greek column greatly increases.

Matt 7:15 δε

Very few witnesses (ℵ B Ω 565. 1424 pc), followed by Bover, Greeven, Lachmann, Merk, and Tischendorf (8th), omit δε after προσεχετε, while all others predating the 10th century retain it (including C E G K L M O S U V W X Δ Θ Π Σ Φ 047 0211 0281 Byz f1.13.35 33. 892. 1500. 2224*), which Soden, Tischendorf (7th), and Vogels support. Weiss (159) comments that "omission of δε through scribal error is of course very frequent . . . especially after προσεχετε, as in ℵ D in Luke 21:34, D in Matt 10:17 and 16:11, B D Δ Byz in Matt 6:1, and ℵ B in Matt 7:15, where only Tregelles in brackets retains it." Bloomfield (GNT, 1:53; Annotations, 6), in addition to mentioning that the conjunction was "lost by the carelessness of scribes, who often omit δε," later judges that it was "more probably removed by critics unable to follow up the thread of the connexion . . . , and who, observing its absence from the lectionaries, where from a lectio commencing with this verse the particle could not be used, accordingly expunged it." In addition to mere accident (-ΤΕ followed by ΔΕ) and possible lectionary influence, the omission could also have been facilitated by an early versional diglot that omitted the word, as almost certainly occurs with the omission of the same word after προσεχετε in Matt 10:17 (by D it sy-s sa-mss mae). Although far less likely, it is possible that some manuscripts omit the conjunction by assimilation to Matt 6:1, where δε is missing after προσεχετε in 3 of the 5 pre-10th-century manuscripts that omit it here (i.e., B Ω 565). For literature on the prevalence of omission (especially of smaller words/particles) over addition in the early period, see the note on Matt 1:22 του. See also the note on Matt 6:1 προσεχετε, where reasons are adduced why the δε in that case may not be primary.

Matt 7:13 εισελθετε

As in Matt 2:5 ειπον and Matt 5:1 προσηλθον, here some manuscripts (ℵ B C L N O W Δ Θ Σ Φ f13 33. 1424 al) and editors (Bover, Greeven, Lachmann, Merk, Soden, Tischendorf, Vogels) favor the supposedly Alexandrian spelling εισελθατε (with an -α-) over the more common spelling εισελθετε (with an -ε-), represented by most manuscripts (including E G K M S U V X Π Ω [047] 0211 Byz f1.35 565. 1500. 2224).  Wordsworth (25) notes that εισελθατε is an alteration in favor of the Alexandrian pronunciation, which, for example, favors the first person singular forms ἔφυγα, ἔλαβα, and εἶδα (for ἔφυγον, ἔλαβον, and εἶδον, respectively) and the third person plural forms ἔφυγαν, ἔλαβαν, εἶδαν, εὗραν, ἦλθαν, εἶπαν (for ἔφυγον, ἔλαβον, εἶδον, εὗρον, ἦλθον, and εἶπον, respectively). That particular phenomenon perhaps developed and was popularized to distinguish the otherwise identical first person singular and third person plural forms. But there is little reason to suppose that the NT authors would have preferred the "Alexandrian" forms any more than they would the common ones. For many examples of sporadic alterations away from the -ο- form toward the "Alexandrian" -α- form in primary Alexandrian witnesses, see Soden, 1:1392. From the same source, several examples more directly related to the present case of εισελθετε vs. εισελθατε include:

Matt 6:10 - ελθατω (ℵ D G W Δ)
Matt 10:13 - ελθατω in (ℵ C L N W f13 33)
Matt 26:39 - παρελθατω (p37vid ℵ A C D E F G H L Δ Θ Ω 33)
Mark 13:15 - εισελθατω (ℵ A D L Δ f13)
Luke 11:2 - ελθατω (p75 ℵ C P W Δ f13)
2 Cor 6:17 - εξελθατε (p46 ℵ B C F G 33)
Rev 18:4 - εξελθατε (ℵ A)

Trivialities of this sort generally play little role in New Testament textual criticism, except perhaps in the chance that the provenance of a manuscript might be guessed by means of attention to such matters.

Matt 7:12 αν

The form εαν (ℵ C O W Θ Σ f13 1500) is favored by Bover, Greeven, Merk, and Tischendorf (8th), but Lachmann, Soden, Tischendorf (7th), and Vogels print αν as in most manuscripts (including B E G K L M N S U V X Δ Π Φ Ω 047 0211 Byz f1.35 33. 565. 1424. 2224). Weiss (86), but probably too mechanically, receives αν on the ground that critics preferred εαν after the relative pronoun. While such might explain the presence of εαν in some witnesses (e.g., ℵ C Θ), it is at least as likely that in the other witnesses (i.e., O W Σ f13 1500) scribal assimilation to the εαν form that occurs in 7:9, 10 may be blamed. Since Matthew is not averse to using both forms (cf., e.g., 5:19, 32, where both constructions appear even in the same verse), and in light of the above considerations, it seems best not to spurn the well-supported αν in this place.