Is it permissible to complete a contract that contains an invalid condition?

Question:
If a person wants to conclude a contract with some people, and they want to impose an invalid condition on him, and he wants not to inform them until the contract is completed, and then say: the condition is invalid, is that permissible?

Answer:
No, he should inform them. He does not complete the condition. He informs them that the condition is invalid. He does not conclude the contract for them. He clarifies it to them. He does not deceive them.
Q: It came in the hadith this...?
The Shaykh: ... He informs them. The Messenger of Allah (peace and blessings be upon him) informed them. He said: Teach them, and inform them that the contract is invalid, that there is no harm in buying her and the loyalty belongs to her .
Q: In some narrations, it is stated that he said to Aisha: ?
The Shaykh: Because he conveyed it to them. As long as they were informed, it is a matter of reprimanding them and blaming them. That is to say: whether you stipulated it or not, you have been informed that it is not permissible.