For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
The statement in one of the answers that Tenebrae is "an ancient tradition in "Christian" history, should more honestly be explained as a tradition of men put in place by The Roman Catholic Church as a Roman Rite. Also including the reform of the Holy Week ceremonies by Pope Pius XII in 1955, the Easter Vigil, moving Easter liturgy from Holy Saturday morning to the following night and, the principal liturgies of Holy Thursday and Good Friday.
If you read your bible we are to avoid the traditions of men and adhere to God's Word and His Word alone, not adding to or taking away. …"Mark 7 They worship Me in VAIN; they teach as doctrine the precepts of men.’ 8You have disregarded the commandment of God to keep the tradition of men.” 9 He went on to say, “You neatly set aside the commandment of God to maintain your own tradition.…"
Tenebrae is NEVER mentioned in scripture, neither is Easter, Good Friday etc. Those are man's holy days and traditions, not God's.