Vous avez cherché: an idle brain is the workashop of satan (Anglais - Swahili)

an idle brain is the devil's workshop
bongo mvivu ni warsha ya shetani

surely scheming is the work of satan that he may cause the faithful grief; but he cannot harm them unless god dispense.
kwa hakika minong'ono hiyo inatokana na shetani ili awahuzunishe walio amini, na wala haitawadhuru chochote ila kwa idhini ya mwenyezi mungu.

mankind! eat of whatsoever is, the earth, lawful, and clean and follow not the footsteps of satan; verily he is an enemy unto you manifest.
kuleni vilivyomo katika ardhi, halali na vizuri, wala msifuate nyayo za shet'ani. hakika yeye ni adui yenu aliye dhaahiri.

conspiracy for evil purposes is the work of satan, by which he means to bring grief to believers. but he cannot harm them in the least, unless it be by god's leave.
kwa hakika minong'ono hiyo inatokana na shetani ili awahuzunishe walio amini, na wala haitawadhuru chochote ila kwa idhini ya mwenyezi mungu.

the one of his party appealed for his help against his enemy, moses struck and killed him, and said: 'this is the work of satan, he is surely a clear, misleading enemy.
musa akampiga ngumi, akamuuwa. akasema: hiki ni kitendo cha shet'ani; hakika yeye ni adui, mpotezaji dhaahiri.

those who believe fight in the cause of allah, and those who reject faith fight in the cause of evil: so fight ye against the friends of satan: feeble indeed is the cunning of satan.
walio amini wanapigana katika njia ya mwenyezi mungu, na walio kufuru wanapiana katika njia ya upotofu. basi piganeni na marafiki wa shet'ani.

moses struck his enemy to death, but later said, "it was the work of satan; he is the sworn enemy of the human being and wants to mislead him".
akasema: hiki ni kitendo cha shet'ani; hakika yeye ni adui, mpotezaji dhaahiri.