Day 36 of 40 is a witness to the resurrected Christ.

"In Acts 1:8, Jesus lays out the plan of attack for His disciples as His witnesses. When the Spirit comes, they will witness of Him in Jerusalem, in Judea and Samaria, and to the uttermost part of the earth. Acts reflects this three-pronged program."(Dr. Timothy Berrey, "40 Days Through The Bible")