Is the one who shows off in the supererogatory acts punished the same as one who shows off in the obligatory acts, or is there no sin upon him because the deed is not an obligation, knowing that showing off nullifies the deed?

Hypocrisy (Riyaa') in worship is forbidden by the Qur’an, the Sunnah, and the consensus of the Ummah. It is considered minor shirk (polytheism), as the worshipper does not intend to seek the countenance of Allah the Almighty, but rather desires to show off his worship to people to gain money, status, or praise. Hypocrisy manifests itself in dress, speech, and actions. The one who commits it is sinful, and his deed is considered void. If hypocrisy does not involve intending to glorify other than Allah, then it is not major shirk, but rather a subtle shirk resulting from glorifying the created. As for showing off in permissible matters, such as beautifying oneself for people, it is not forbidden as long as it does not involve deception or mockery of religion.