To help you figure out what's inside or if it's safe, you might want to look at:
Check if the site provided an MD5 or SHA-1 hash. Comparing your file's hash to the provided one is the only way to verify the "part4" isn't corrupted. 948E8GT95CB689T8A824.part4.rar
If you have the file, tools like VirusTotal can "review" it for security by scanning it against dozens of antivirus engines. To help you figure out what's inside or
Reviews or comments on the specific forum, blog, or tracker where you found the link often provide the best "review" of the content's quality and authenticity. Reviews or comments on the specific forum, blog,
Since this looks like part of a multi-part set, you will typically need (part1, part2, etc.) in the same folder to extract the actual content.
Do you have the or the context of where this file was listed? Knowing that would help me identify what the actual "topic" or content is.