But Bengel (Apparatus, 110) judges that the singular entered from the following verse, and further explains (Gnomon, 195–6): "The objects which are mentioned in ver. 22, 23 (consequentia) are in the singular, those which are mentioned in ver. 19, 20 (antecedentia), with which this verse is connected, are in the plural number. The plural therefore must stand in this verse. The singular, 'thesaurus tuus,' 'thy treasure,' easily crept into the Latin Vulgate, and was convenient to the Greeks for ascetic discourses." Wettstein (1:330) rejects the minority reading because in his judgment the witnesses for it are "not very reliable." Bloomfield (GNT, 48) says that σου "was doubtless an alteration to adapt the word better to the singular σου at the next verse; the purblind Critics failing to see that the plural υμων is as suitable to a general injunction as the singular σου is to a particular illustration, which is made such for effect's sake. Thus at v. 24 the plural form is resumed, when the language of injunction is resumed."
The saying assumes a wide variety of forms in the church fathers:
Hans Dieter Betz (The Sermon on the Mount [ed. Adela Y. Collins; Hermeneia 54; Minneapolis: Fortress Press, 1995], 437) notes the possibility that an older proverb has been purposefully deplatonized in Matt 6:21, which Justin and Clement have replatonized. Text-critically, an original plural υμων with the singular θησαυρος and καρδια could have provoked natural alterations, such as (1) a change to the third person singular (Justin, Clement, Origen, John Chrysostom), (2) the elimination of the plural pronoun (Origen, Gregory of Nyssa), (3) a change to conform the number of the pronoun to the number of the noun (Eusebius, Ephrem, Basil of Caesarea, Evagrius Ponticus). If Betz' hunch is correct and the saying in the tradition upon which Matt 6:21 hangs had singular genitival nouns/prounouns, this also might explain the wide diversity away from the plural. Additionally, one might argue a common Caesarean origin behind those few witnesses that read soυ (ℵ B 1. 372. 1582) and certain fathers who do so (Eusebius, Basil, Evagrius), although alteration to the second person pronoun for homiletical reasons could also have been in effect.