With regard to copying text into your work, permission should be acquired for use of long quotations or excerpts - unless fair dealing or a similar provision applies (e.g. multiple pages from a book). A short quote that you would include in the body of your text would not require copyright permission and a block quotation would not necessarily require permission. 

There is no exact word count that is the maximum amount of text that could be used before permission is required. If you are unsure about what constitutes a long quotation (which may require permission if fair dealing or a similar provision doesn’t apply), you can consult with your subject librarian. The MRU citation style guidelines (e.g., APA, MLA, etc.) may include helpful information on this as well.