وَعَنْ عُمَرَ عَنِ
النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «لَا يَخْلُوَنَّ رَجُلٌ بِامْرَأَةٍ إِلَّا كَانَ ثالثهما الشَّيْطَان»
Umar reported the Prophet (sallallahu alayhi wa sallam) as saying, “Whenever a man is alone with a woman the devil makes a third.”
Mishkat al-Masabih 2994, Book 14, Marriage, Hadith 39. 1 min read