It is narrated from Sayyiduna Malik bin Ukhaymir (may Allah be pleased with him); he said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Indeed, Allah does not accept from the suqqur any voluntary deed or any obligatory one." It was said: O Messenger of Allah! Who are the suqqur? He (peace and blessings be upon him) said: "The one who lets a (strange) man come in upon his family."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 16703