In Craig Blomberg's article, "On Wealth and Worry: Matthew 6:19-34—Meaning and Significance", Criswell Theological Review 6.1 (1992), 73-89, on p. 74 at footnote 7 he notes:
There is... an important "catchword" connection between the uses of ἀφανίζω in 6:16 and 6:19-20. See A Sand, Das Evangelium nach Matthaus (Regensburg: Pustet,1986) 19-21."
The verses in question read as follows:
Matt 6:16 Whenever you fast, do not put on a gloomy face as the hypocrites do, for they neglect their appearance [ἀφανίζουσιν] so that they will be noticed by men when they are fasting. Truly I say to you, they have their reward in full.
Matt 6:19 “Do not store up for yourselves treasures on earth, where moth and rust destroy [ἀφανίζει], and where thieves break in and steal. 20 But store up for yourselves treasures in heaven, where neither moth nor rust destroys [ἀφανίζει], and where thieves do not break in or steal;...
Can someone provide additional explanation as to this connection?