ends of the earth, the
The utmost limit, as in She would go to the ends of the earth for him. This usage was once literal (referring to the farthest reaches of the planet) but now is used only figuratively.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.