杀鸡焉用牛刀

shā jī yān yòng niú dāo

don't use a sledgehammer on a nut

aquila non capit muscam

shā

to kill; to slay; to murder; to attack

variant of 雞|鸡[ji1]

yān

where

yòng

to use; to make use of; to employ

niú

ox

dāo

knife; blade; single-edged sword; cutlass (CL:把[ba3])