Austin Kleon wrote in his book Show Your Work! about the importance of sharing where you found things.
Crediting work in our copy-and-paste age of reblogs and retweets can seem like a futile effort, but it’s worth it, and it’s the right thing to do. You should always share the work of others as if it were your own, treating it with respect and care.
But maybe even as important as linking the original source is linking how you found the thing. There are so many times when because of following "via" or a chain of reblogs that I could discover so many new blogs I liked.
Link the source. Link where you found it. Make it easy for others to find the same thing. This makes you a nice person to the original author, and to the people who curated it along the way.