Is it necessary to recite Surat Al-Mulk immediately before sleeping if it has already been recited during the 'Isha prayer?

Regarding the virtue of reciting Surah Al-Mulk before sleeping, it is narrated by Al-Tirmidhi from Abu Hurayrah, may Allah be pleased with him, who reported that the Prophet, peace and blessings be upon him, said: "Indeed, there is a Surah in the Qur’an of thirty Ayat that interceded for a man until he was forgiven, and it is 'Tabarak Alladhi bi Yadihi al-Mulk' (Blessed be He in Whose Hand is the dominion)."

Al-Tirmidhi also narrated from Jabir, may Allah be pleased with him, "that the Prophet, peace and blessings be upon him, would not sleep until he recited 'Alif Lam Mim Tanzil' (Surah As-Sajdah) and 'Tabarak Alladhi bi Yadihi al-Mulk' (Surah Al-Mulk)."

It is preferable to recite it every night before sleeping, as this was the practice of the Prophet, peace and blessings be upon him. It is also sufficient to recite it during the 'Isha prayer, or during the night prayer before sleeping, or before that; due to the generality of the first Hadith regarding the intercession of the Surah for whoever recites it, and it does not specify a particular time for its recitation.

However, it is not prescribed to consistently recite it in the 'Isha prayer, because consistency is a form of restriction that should only be done if there is a دليل (proof). If it is done occasionally, there is no harm.