It is basic to writing to site your sources. If it is a direct quote, write it as a quote and site the source. Even when you are writing about what someone said; be it a paraphrase are you have used there writing to come to an understanding of something you always site the source. This is true of writing, sound bites, pictures, and videos. The style is dependent on the type of writing that one does. For example if you are writing a scientific paper you use APA citatation. If you are writing a theology paper you use Turabian citation. But in whatever you are writing site the source. Should social media be any different?