E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Bread.
He took bread and salt, i.e. he took his oath. Bread and salt were formerly eaten when an oath was taken.
1
Cast thy bread upon the waters: for thou shalt find it after many days (Eccles. xi. 1). When the Nile overflows its banks the weeds perish and the soil is disintegrated. The rice-seed being cast into the water takes root, and is found in due time growing in healthful vigour.
2
Don’t quarrel with your bread and butter. Don’t foolishly give up the pursuit by which you earn your living.
3
To know which side one’s bread is buttered. To be mindful of one’s own interest.
4
To take the bread out of one’s mouth. To forestall another; to say something which another was on the point of saying; to take away another’s livelihood. (See under BUTTER.)
