186. The authority to declare something prohibited rests with whom? 

These two verses (7:157, 9:29) of the Quran declare that the authority to rule over prohibitions rests with Prophet Muhammad

The Almighty has the authority to prohibit or allow anything, and no one has the power to ban anything allowed by Allah, neither can they allow something restricted by Him.

The verses 5:87, 6:138,139, 6:150, 7:32, 10:59, 16:116 of the Quran clearly state that the authority to prohibit anything that is permitted rests with Allah alone.

But these two verses (7:157, 9:29)of the Quran speak of Allah having granted Prophet Muhammad with the said powers. .

This should not be treated as a contradiction to the above quoted verses.

Because just as Prophet Muhammad used to receive messages from Jibreel (A.S), he got messages from the Almighty through other means.

Based on these messages he used to declare acts, as prohibited and others as permitted 

And the verse (66:1) of the Quran saying “ How can you declare those that are permitted by Allah as prohibited” as a contradiction. In this verse the Quran does not speak of things prohibited to public at large, rather it speaks of a specific matter where Prophet Muhammad self denied himself something that was not banned.

There is nothing wrong in a person avoiding things that he dislikes , but Prophet Muhammad though he liked honey, he avowed not to touch it for other reasons. This is what the verse (66:1) points out. This can be understood by the sentences.``Why do you do this to appease your wives”

For more details please refer to explanation points 42, and 272.