The first 4 links in Google:-
www.mozilla.com/firefox/ - 15k - Cached - Similar pages
(mozilla make firefox and offers the latest version)
Mozilla.org - Home of the Mozilla Project
Get Firefox now at Mozilla.com Get Thunderbird now at Mozilla.com ... Looking for Firefox or Thunderbird? You'll find them and a whole lot more at ...
www.mozilla.org/ - 12k - Cached - Similar pages
Same website as above
Mozilla Downloads
Firefox 1.5.0.7 · Firefox 1.5.0.7. Our next generation browser is here. Enjoy! download: Windows (4.9MB), Linux (8.1MB), Mac OS X (16.1MB), More… ...
www.mozilla.org/download.html - 11k - Cached - Similar pages
Firefox.com
The Mozilla Foundation thanks Kevin Karpenske, the previous owner of the Firefox.com domain, for generously having transferred this domain to our use for ...
www.firefox.com/ - 3k - Cached - Similar pages
Another page which also points to
www.mozilla.com/firefox.
Its not hard to use google

And its pretty safe to do so - its also safe to ask the question as you did however. Downloading it from someones blog is a dangerous thing to do....