1. Leviticus 16:13 (ESV)
  2. Exposition

What was done to the incense?

Leviticus 16:13 (ESV)

13 and put the incense on the fire before the LORD, that the cloud of the incense may cover the mercy seat that is over the testimony, so that he does not die.

Aaron was required to take fragrant incense that has been ground to a fine consistency and put it on the fire. This created a cloud within the Most Holy Place.