Keeping a beard
Q:
1. Can I know any authentic hadith and examples other than that of Ibn Umar (radhiyallahu anhu) of cutting a fistful of the beard?
2. When we say cut a fistful of the beard (exceeding one fist), from where do we take 1 fist? How do we know this? Is there any authentic source which mentions that one fist is from the chin or do we just assume it?