What is the ruling on one who deliberately completes "Sami' Allahu liman hamidah" (Allah hears the one who praises Him) after rising from bowing, or completes the takbir of prostration while already prostrating?

The man's prayer is valid, as the takbirat (saying "Allahu Akbar") and tasmee' (saying "Sami'a Allahu liman hamidah") are Sunnah according to the majority of scholars, and obligatory according to the Hanbalis. Their proper place is during the transition between prayer postures. They are excused if performed out of place due to the difficulty of strict adherence.