ما هي سورة المصابيح؟

There is no surah in the Qur’an called "Surat Al-Masabih" (The Surah of Lamps). Perhaps the questioner is referring to what Usaid ibn Hudair (may Allah be pleased with him) saw when he recited Surat Al-Baqarah, where a cloud-like canopy descended, containing what resembled lamps. The Prophet (peace and blessings be upon him) informed him that these were angels who had drawn near to listen to his voice. Surat Al-Baqarah is not called Surat Al-Masabih, as the names of the surahs are divinely ordained.