Should the worshipper who caught the last two rak'ahs of a four-rak'ah prayer recite the entire Tashahhud and pray upon the Prophet (peace be upon him)?

If a latecomer (masbūq) catches the last two rak'ahs of a four-rak'ah prayer, and the Imam sits for his final tashahhud, the latecomer must sit with him. Scholars differed on what the latecomer should say during this sitting. Some went to the extent that he should not add anything beyond the first tashahhud and repeat it. The Shafi'is, however, went to the extent that he should say during this sitting what he would say in the final tashahhud.

The preponderant view is that of the Shafi'is, because sending blessings upon the Prophet and supplicating were only prohibited in the first tashahhud for the sake of lightness, whereas in this matter, there is no such prohibition.