Matt 6:6 ταμιειον

Although a minority of witnesses (ℵ B D E L W Θ Σ 35 700 1241 al [ℵ D W Θ: ταμιον]) and the so-called revised Koine text (Kr/f35) have the more common contracted form ταμειον (cf. Matt 24:26; Luke 12:3, 24), most manuscripts and many editors (e.g. Lachmann, Tregelles, von Soden, NA25, etc.) retain the uncontracted ταμιειον (including K M S U X Z Δ Π Φ Ω f1.13 33 579 1424; Or). For the other occurrences of the word in the NT most manuscripts have the contracted form with only a small minority retaining the uncontracted form:

Matt 24:26 ταμειοις (but ταμιειοις: L S X Γ Ω f1 33 pc; Or)
Luke 12:3 ταμειοις (but ταμιειοις: K S Ψ Ω f1 pc)
Luke 12:24 ταμειον (but ταμιειον: F M S U Ω f1 33 579 1424 pc)

This circumstance heightens preference for the uncontracted ταμιειον here, since there is no reason why most scribes would have written the uncontracted form only here. In other words, the nonconformed reading, in this case ταμιειον, is to be preferred. Von Soden (1:1370) also suggests that the uncontracted form represented by a minority of manuscripts in Matt 24:26, Luke 12:3, 24 further corroborates the original presence of that form in Matt 6:6. Lastly, the accidental dropping of the letter iota in words of similar spelling is observed elsewhere, such as, e.g., συνειτε in B in Mark 8:17 (instead of συνιετε).