Does it negatively impact search rankings for page to have hyperlinks in the body content that link back to itself? For example: I have a page that has tabs, which describe different products on each tab [ex: website.com/product.html#tab3]. All the tabs contribute to the on-page content. Each tab has unique and targeted content. So, if the tabs include links back to the product.html page without the #tab, will that have negative impact? Or can I link between the pages both with and without the #tab as much as the content requires?
I don't think it will hurt your rankings to have a link to another page in your site from a tab as well as from the content of the page. Just remember that when you're designing your site the reader needs to come first. The navigation of the site needs to be smooth. You want your readers to be able to move around the site easily. If making another page available through a link in a tab as well as from the content is helpful then do it. Too many links from one page to another page on the site is not user friendly.
I highly recommend this - I've had great results with sites doing just this. Tip: If you're using Wordpress you can add this automatically at the end of each post by modifying the loop file.
I don't think it will negatively impact the ranking of the webpage, so long as those links are relevant to what the webpage is discussing. If your users/readers find the page helpful, then Google will rank that page highly, regardless of the number of links on that page. Hope that helps. Have a good day!