You do not necessarily need to put it in quotations but it is important to make clear when you are referencing someone's work. It should be clear when there work starts and stops. If you are going to paraphrase something again you should make it clear and reference the original work.
Dan Smith - "The cat sat on the mat"
In a piece of work the renowned author and poet Dan Smith once said "The cat sat on the mat".
Having read the work of Dan Smith he stated that a feline animal was placed on a piece of floor covering.
Both are acceptable but in either case it is clear you are talking about Dan Smith's work.