Albert Barnes Commentary Mark 4:24

"And he said unto them, Take heed what ye hear: with what measure ye mete it shall be measured unto you; and more shall be given unto you." — Mark 4:24 (ASV)

Take heed what you hear. Or, consider well what you hear. Make good use of it.

With what measure you measure, etc. You will be treated according to the use you make of your opportunities of learning. If you consider it well, and make good use of what you hear, you will be well rewarded. If not, your reward will be small. This is a proverbial expression. (See Barnes on Matthew 7:1-2).

Mete. Measure. With what measure you measure.

Unto you that hear. To you who are attentive, and who make good use of what you hear.