背に腹は替えられぬ
Meanings
1
you can't make an omelet without breaking eggs; a small sacrifice may be necessary to solve a more pressing problem
Proverb meaning that to deal with a greater problem, one must sometimes endure a lesser loss or sacrifice. Literally 'you can't replace your belly with your back' — the belly (vital) cannot be sacrificed for the back (less vital).
See also: 背に腹は変えられない
You can't make an omelet without breaking eggs, so some expense is unavoidable.
As the saying goes, a small sacrifice may be necessary; he took on the unpleasant job.