Jesus illustrates two sowers of different character. In the Parable of the Sower, the sower stands for all teachers of God's truth, including Jesus. Here, "the sower" is exclusively Jesus. He is the "owner", and "the son of Man". The other sower is called "his enemy," "an enemy," "the wicked one," and "the devil". To describe this enemy, Jesus uses the word diabolos: the accuser, deceiver, liar, and betrayer, one who is against all that is true and righteous.
The enemy sowed in a field that was not his while the servants slept. This does not necessarily mean that the servants were not watchful and were thus to blame for the mixed field. The wording implies that it was the normal time for sleep, night. Satan's sly nature is revealed in his choice of the darkness for doing his diabolical work. Also, note that he does not bother to sow the wicked among the wicked, but the wicked among the good.