In Ezekiel 4:15, this signifies that the prophet was to represent the corruption of the literal sense of the Word. (The Inner Meaning of the Prophets and Psalms 127)

127. Internal Meaning of Ezekiel, Chapter 4

Representation of the perverted church in the church. (2)

1-2 He should represent the falsities of the church, and the church besieged by them. (2)

3 He should represent the hardness of their heart, from which it is that they have no fear; (2)

4-8 he should also represent the church besieged by falsities of evil and evils of falsity. (2)

9-16 He should represent the falsification and adulteration of the sense of the letter of the Word, (2)

17 by which everything of the church has perished. (2, 3)