doorpost

Definition:

The "doorpost" is a vertical beam on either side of a door, which supports the top of the door frame.

Just before God helped the Israelites escape from Egypt, he instructed them to kill a lamb and put its blood on their doorposts.
In the Old Testament, a slave who desired to serve his master the rest of his life would place his ear on the doorpost of his master's house to have a nail hammered through his ear into the doorpost.
This could also be translated as "wooden post on either side of a door" or "sides of a wooden doorframe" or "wood beams on the sides of a doorway."