This verse is in quotes and in the translation I read, it stood alone all by itself as if it is intended to be visible and clear to all. Some have used this to demand or force Tithes from others. But here is my take on it below.
God made this statement to His people knowing He had already blessed them and He expected, because He had blessed them and knew they were blessed, that no one would come to Him without bringing a blessing from what He had given them. So from what He has given you, offer from it to Him an offering and/or Tithes.
Exodus 34:20
20 “No one is to appear before me empty-handed.