What is the ruling on the prayer of one who intentionally recites aloud in the first unit of prayer (rak'ah) then silently in the second, whether in a prayer that is to be recited aloud or one that is to be recited silently?

Whoever intentionally recites aloud in the first rak'ah and silently in the second has committed a reprehensible act (makruh), but their prayer is valid. This is the view of the Shafi'is and Hanbalis. However, the Malikis, Al-Thawri, Abu Hanifa, and Ishaq said that one should perform the prostration of forgetfulness (sujud al-sahw), and according to one opinion among the Malikis, the prayer becomes invalid.