God tells Ezekiel he will be made mute and unable to reprove the people, because they are a rebellious house Ezekiel 3:26. He also says he will open Ezekiel’s mouth when it is time to speak the message Ezekiel 3:27. The text links Ezekiel’s speaking directly to God’s opening his mouth Ezekiel 3:27.
In Ezekiel 3:24–27, Ezekiel is put under strict limits on his movement and speech. The Spirit sets him on his feet and orders him to shut himself in his house. He is told that others will bind him so he cannot go out among the people. This passage sits inside Ezekiel’s call and commissioning narrative (Ezekiel 1–3). After seeing the vision and receiving his assignment, Ezekiel is being shaped into a messenger whose words and actions are tightly controlled by God.
The passage presents Ezekiel’s prophetic work as tightly controlled by God. The Spirit sets him up to receive instruction, but the first instruction is seclusion: he is told to shut himself inside his house. That physical restriction is matched by a speech restriction: God says Ezekiel will be unable to speak, except when God chooses to “open” his mouth.
A careful answer keeps the immediate passage, the book's argument, and the whole-Bible storyline together, so the question is answered in context instead of as a detached idea.
Start with Ezekiel 3:26, then read the surrounding section so the answer stays connected to the passage's flow.
26and I will make your tongue cleave to the roof of your mouth, that you shall be mute, and shall not be to them a reprover; for they are a rebellious house.