[Abu 'Eisa said:] There is a narration on this topic from Ibn 'Umar.
The Hadith of Anas is a Hasan Sahih Gharib Hadith.
This is acted upon according to the people of knowledge. They say that the free man can be prevented from selling and buying when his intellect is weak. This is the view of Ahmad and Ishaq. Some of the scholars did not think that the free person who had attained the age of responsibility could be prevented from that.
In-book : Book 14, Hadith 50
English translation : Vol. 1, Book 12, Hadith 1250