I finally took some time and wrote the simple .htaccess rule for redirecting traffic from farhan-ahmad.net to thebitguru.com. Both the domains are served through the same directory so I just updated the .htaccess file and added the following rules above the Rails rules.
RewriteCond %{HTTP_HOST} (www.)?farhan-ahmad.net$ [NC]
RewriteRule ^(.*)$ https://thebitguru.com/$1 [L,R]