- "Teachers are hereby banned from giving students any information that is not strictly related to the subjects they are paid to teach"
- —The Decree[src]
Educational Decree Number Twenty-Six was the third Educational Decree created by Dolores Umbridge in her capacity of Hogwarts High Inquisitor.  This Decree forbade the teaching body from giving the students any information that was not related with the subjects they were hired to teach.
Educational Decree Number Twenty-Six was passed by Dolores Umbridge, then-Hogwarts High Inquisitor on 14 January, 1996 to prevent the teachers from discussing the mass breakout from Azkaban that had occurred the day before. 
After the Decree was passed, small groups of two or three professors would be found around the school talking in a low and urgent voice, discontinuing their conversations every time a student approached. As the teachers were apprehensive about this Decree, the students made it the object of many jokes; Lee Jordan quoted the Decree to Umbridge when she told off Fred and George Weasley for playing Exploding Snap in her Defence Against the Dark Arts class. As a result, he was forced to write lines with her Blood Quill. Harry Potter felt rather furious at this new decree, as it proved that Umbridge was not the least persuaded by the Azkaban breakout of Voldemort's return, but instead she continues to undermine the Order of the Phoenix's attempt to get the message out.
The teachers were forbidden from praising Harry Potter directly for his interview in The Quibbler due to this Decree, but they circumvented this by awarding him with other means, Professor Sprout by awarding Gryffindor House twenty points for simply passing a watering can, Professor Flitwick gave him a box of Sugar Mice, and Professor Trelawney diverged from her usual prediction of Harry's death by claiming that he would live long with twelve children and become the Minister for Magic. Additionally, once students began making trouble en masse following Umbridge's appointment as Headmistress, the teachers did not trouble to help Umbridge, with Flitwick stating that he could have gotten rid of Fred and George's fireworks, but he was not sure whether he had the authority.
The decree was abolished after Dolores Umbridge's suspension from her post of High Inquisitor and Albus Dumbledore's return to his post of Headmaster, following the Battle of the Department of Mysteries in the spring of 1996.
Behind the scenes
- In the film of Harry Potter and the Order of the Phoenix, this was Educational Decree Number Seventy-Seven instead.