shā jī yān yòng niú dāo
don't use a sledgehammer on a nut
aquila non capit muscam
杀
shā
to kill; to slay; to murder; to attack
鸡
jī
variant of 雞|鸡[ji1]
焉
yān
where
用
yòng
to use; to make use of; to employ
牛
niú
ox
刀
dāo
knife; blade; single-edged sword; cutlass (CL:把[ba3])