How can I translate an article from another site and post it to mine without SEO damage?

Most of my blog posts are written by me, but I'd like from time to time to publish articles in other languages that I can translate by myself. Obviously I'd mention the source. But researching this topic I am confused and a little afraid it will harm my SEO. What do you think? What experience have you had? Are there any SEO best practices for publishing translated content from another source? Thanks!