Matt 6:1 προσεχετε

Some manuscripts (including ℵ L Z Θ f1 33 892 1241 1424 al g1 sy-p.h bo) reflect either scribal error or dissatisfaction with the absence of a transitional conjunction, adding δε after προσεχετε. But most witnesses from a wide variety of traditions (i.e., Alexandrian, Western, Byzantine, Old Latin, Old Syriac, Middle Egyptian) refrain from the addition (B D E K M S U W Δ Π Σ Ω 047 0250 f13.35 565 lat sy-c mae-1 bo-mss goth).
     Had only some witnesses with less diversity omitted the conjunction, one might suspect omission by homoeoteleuton error (ε...ε). Perhaps the addition was facilitated by the initial reduplication of -τε (cf., e.g., ℵ in Mark 11:25; D Θ in Matt 13:48; p37vid in Matt 26:38) followed by the correction of τε to δε, or, especially due to the scribal propensity to err due to the circumstances of continuous script, the initial mistaking or "correction" of -τε to δε, which occurs elsewhere in the NT (e.g., Acts 2:43 [ℵ B 81]; 2:46 [p74]; 4:13 [p74 D Ψ 0165*]; 5:19 [B Ψ 0189]; 8:28 [B C]). Cf. also 1 Cor 6:9–10, where D/06 and E/07 alter 8 occurrences of ουτε into ουδε.