Final answer:
The Holy Night during which the Holy Quran was first revealed is known as Laylat al-Qadr, which is the most sacred night for Muslims marking the beginning of the Quran's revelation.
Step-by-step explanation:
The Holy Night during which the Holy Quran was first revealed is Laylat al-Qadr. According to Muslim belief, this was the night when the Quran was first sent down from Heaven to the world. The precise date of Laylat al-Qadr is not definitively known, but it is believed to occur on one of the odd-numbered nights in the last ten days of the month of Ramadan, the ninth month in the Islamic lunar calendar. Laylat al-Qadr is considered the most sacred night of the year for Muslims as it marks the beginning of the revelation of the Quran to Prophet Muhammad by the Angel Gabriel.