ㄎㄞkāiㄇㄣˊménㄉㄠˋdào

  1. 開門揖盜比喻引進壞人招禍梁書··》:大逆不能浮說開門揖盜。」南史··梁簡文帝本紀·》:開門揖盜。」引狼入室

leaving the door open invites the thief (idiom)​; to invite disaster by giving evildoers a free hand
das Unglück heraufbeschwören (Sprichw)​