One particular difference between Sunni and Shi'a Muslim days/nights of observance - July 23 and 10 days that end Ramadan

from Center for Spiritual and Ethical Education dot-org: July 23, 2014 Laylat al-Qadr (Islam) Meaning loosely "the night of power," this is identified as the night in which God first revealed the Qur'an to Prophet Muhammad. It is believed that this day holds more power in prayer than one-thousand months; thus many Muslims spend the whole day in prayer and reading the Qur'an. Sunni Muslims traditionally observe Laylat al-Qadr on the 27th day of Ramadan, while Shi'is believe the 23rd day to be the most important. Since the specific day of the revelation is uncertain, many Muslims spend the last 10 days of Ramadan focused on prayer. http://www.csee.org/resources/religious-calendar/july.html