Forbear means to refrain, to hold back, or to tolerate in the face of provocation. Its past tense is forbore, and its past participle is forborne. It’s usually pronounced for-BEAR. Forebear means a person from whom one is descended; an ancestor. It’s usually pronounced FOR-bear.
Examples
These writers use forbear correctly:
Last October, NMT defaulted on a $4 million loan from Silicon Valley Bank, which agreed to forbear from calling in its note. [Mass Device]
The agency promised to forbear on all but six of the four dozen rules that apply to phone services. [Washington Post]
Forbear is very rare. And in fact, it is misused more often that it is used correctly. In these examples, forbear should be replaced with forebear:
The Milestone 2 retains the stylish good looks of its forbear … [What Mobile]
[T]he descendants of Jose Rizal suddenly become very popular among university students of various schools in Metro Manila who want to interview them about their famous forbear. [Manila Bulletin]
And these writers use forebear correctly:
He is seen as a forebear to Bolivia’s contemporary indigenous movement … [The Progressive]
It is thought that the forebear of the cougar migrated from Asia into North America over the Bering land bridge approximately 8 million years ago … [MongaBay.com]
