Passage
But thou, when thou fastest, anoint thine head, and wash thy face;
But thou, when thou fastest, anoint thine head, and wash thy face;
Matthew 6:15 But if ye forgive not men their trespasses, neither will your Father forgive your trespasses.
Matthew 6:16 Moreover when ye fast, be not, as the hypocrites, of a sad countenance: for they disfigure their faces, that they may appear unto men to fast. Verily I say unto you, They have their reward.
Matthew 6:17 But thou, when thou fastest, anoint thine head, and wash thy face;
Matthew 6:18 That thou appear not unto men to fast, but unto thy Father which is in secret: and thy Father, which seeth in secret, shall reward thee openly.
Matthew 6:19 Lay not up for yourselves treasures upon earth, where moth and rust doth corrupt, and where thieves break through and steal:
The verse centers on "thou", "fastest", "anoint", "thine", "head", "wash", and "face". It is saying that the verse draws attention to "thou" and "fastest", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 16's "Moreover when ye fast be not as..." into verse 18's "That thou appear not unto men to...", so "thou" and "fastest" belong inside that flow. In Matthew context, the local focus is Christ, faith, and discipleship.
A plain takeaway is to answer the verse's own emphasis on "thou" and "fastest" with trust shaped by these words, not by a vague optimism outside the passage.