an idle brain is the devils workshop
Definition:  people with nothing meaningful or worthy to think about or commit themselves to, are likely to think of mischief or something bad to do
Usage:  children must be at school, or they will involve themselves in drugs; parents should know that an idle brain is the devil’s workshop

SEPEDI
Translation:  monagano wo o sa šomego ke boralokelo bja sathane
Proverb: go kwa go kwa moloi, motho wa dithuri ga a kwe

XITSONGA
Translation:  byongo lebyi nga riki ku tirheni i vutirhelo bya sathana
Proverb: mbyana yo ka yi nga caci makhamba yi dya matandza

TSHIVENḒA
Translation:  muhumbulo wa vhubva ndi nḓowetshumo ya saṱhane
Proverb: mbilu ya mubva i tama ya si wane