The expression “to quarrel with one’s bread and butter” means: to complain about one’s means of livelihood; to act against one’s best interests.
And many’s the time you’ve seen a child do that, throw his buttered bread or his piece of cake or even the ice-cream cone he’s been whimpering for on the ground in a fit of rage.
The human race has been thus quarreling since the days of Noah, but our English phrase for expressing such lack of reason dates back not more than two centuries.
