September 1, 2017 regular holiday for Eidul Adha in the Philippines
The Eid al-Adha is Islam's holiest festival celebrated annually around the world and an official holiday in Muslim-majority countries like the Philippines.Eid al-Adha commemorates the willingness of Abraham to sacrifice his son Ishmael as an act of obedience to God, before God then intervened, to provide him with a sheep to sacrifice instead.
As mandated through Republic Act (RA) 9849 signed in 2009, the tenth day of Dhu al-Hijjah or the twelfth month of the Islamic Calendar, is hereby declared as a national holiday for the observance of Eidul Adha.
Here's a part of DepEd Order 25, s. 2017 - School Calendar for School Year 2017-2018 indicating September 1, 2017 as a Special non-working holiday.