χερσί

From LSJ

ὃν οὐ τύπτει λόγος οὐδὲ ῥάβδος → if words don't get through, neither a beating will | if the carrot doesn't work, the stick will not work either | whom words do not strike, neither does the rod

Source

French (Bailly abrégé)

dat. pl. de χείρ.

Russian (Dvoretsky)

χερσί: dat. pl. к χείρ.