Adam Clarke's Commentary on the Bible - Matthew 6:16
When ye fast - A fast is termed by the Greeks νηϚις , from νη not, and εσθειν to eat; hence fast means, a total abstinence from food for a certain time. Abstaining from flesh, and living on fish, vegetables, etc., is no fast, or may be rather considered a burlesque on fasting. Many pretend to take the true definition of a fast from Isaiah 58:3 , and say that it means a fast from sin. This is a mistake; there is no such term in the Bible as fasting from sin; the very idea is... read more
John Gills Exposition of the Bible Commentary - Matthew 6:21
For where your treasure is, there will your heart be also. This seems to be a proverbial expression, and contains in it another reason, dissuading from worldly mindedness; because of the danger the heart is in of being ensnared and ruined thereby: and the sense of it is, if your treasure is on earth, and lies in earthly things, your hearts will be set upon them, and be in them, in your bags, your coffers and storehouses; and so your souls will be in danger of being lost; which loss will be... read more