Give credit where credit is due.

Plagiarism is theft, pure and simple, the purloining of another writer’s words.
No matter the excuse—sloppy note-taking, deadline pressure—the penalty can be harsh. Plagiarists often get fired, and even if they escape the ultimate death penalty, their career is tarnished, their story or book tainted. There’s an easy solution. Be honest about where you get your material. Don’t think everything you write has to be original. Writers stand on the shoulders of other writers. 
Thomas Mallon, author of “Stolen Words”, an engaging history of plagiarism, says writers should follow a general rule: “If you think you should attribute it, then attribute it.”