What is the ruling on one who secretly insulted the two Noble Messengers and then repented and regretted it: Is the hadd punishment to be carried out on him, or is repentance sufficient for him? And does he travel to Saudi Arabia for the hadd to be carried out if it is obligatory?

Insulting Allah and the Prophets is an act of disbelief (kufr). And whoever repents, Allah accepts their repentance and replaces their bad deeds with good ones. Scholars have differed regarding whether the punishment of death for insulting the Prophet is waived by repentance. The more preponderant opinion is that execution is a prescribed punishment (hadd) that is the responsibility of the Imam. As for the insulter whom Allah has concealed and whose matter has not been brought before the judiciary, he must conceal himself and strive in repentance and righteous deeds. Allah is Oft-Forgiving, Most Merciful to whoever repents, believes, and does righteous deeds. Whoever Allah conceals in this world, He will conceal on the Day of Judgment.