Is that, then, valid or not? Is he entitled to withdraw his declaration without any basis in Islamic law?

He replied:

The witnesses must not heed her brother’s words, or anyone else’s, and refrain from testifying. Rather, they must give their testimony for Allah’s sake, as Allah and His Messenger have commanded. Her father has no right to revoke his declaration of her sound judgment. Even if it is established that she subsequently developed imprudence warranting legal restriction, imposing that restriction is not her father’s prerogative, but that of the governing authority. Even if her father had never acknowledged her sound judgment, the restriction upon her ceases once she attains sound judgment, whether or not he declares her to have attained it, and whether or not a judge issues a ruling to that effect. If her sound judgment is disputed and two witnesses testify that she possesses it, their testimony is accepted, and no heed is paid to her father or anyone else.

If she has conducted transactions over a period of time, and a witness testifies that she possessed sound judgment during that period, her transactions are valid, even if her father claims that she was under his legal restriction. Allah knows best.

He was asked:

A woman is under legal restriction, and upright witnesses who are not among her unmarriageable relatives have testified to her sound judgment. Is their testimony accepted or not?

He replied:

Yes. If upright witnesses testify to her sound judgment, a ruling recognizing it is issued, even if they are not her relatives. Uprightness, sound judgment, and similar qualities may be known through widespread knowledge, just as Muslims know of the sound judgment of the Mothers of the Believers and other well-known women. Allah knows best.