A scholar says that oral sex within marriage is permissible.

Answer

This unfortunate, miserable 'scholar' must be an agent of Iblees or he is a sexual pervert with a horribly contorted brain. This filthy practice is sub-devil. Even devils do not demean themselves to this abominable gutter-level of perversion.

Besides the spiritual destruction of the soul caused by such unnatural carnality, it causes diseases and even cancer. Read the comments of the kuffaar experts.