Английский словарь американских идиом - turn one's back on

{v. phr.} To refuse to help (someone in trouble or need.) * /He turned his back on his own family when they needed help./ * /The poorer nations are often not grateful for our help, but still we can not turn our back on them./ Compare: GO BACK ON(1). TURN ONE'S HAND TO See: PUT ONE'S HAND TO.