ТОЛЬКО ТОТ, НА ЧЬЕЙ НОГЕ БАШМАК, ЗНАЕТ, ГДЕ ОН ЖМЕТ

Cf:Each organism knows best where it itches (Am.). Every one knows best where his shoe pinches (Br.). Everyone knows where his shoe pinches (Am.). No one but the wearer knows where the shoe pinches (Br.). Only he who wears the shoe knows where it pinches (Am.). The wearer best knows where the shoe pinches (Am.)