Compiled by Imam Yahya ibn Sharaf al-Nawawi
وعن ابن عباس رضي الله عنهما أن رسول الله صلى الله عليه وسلم قال: "لا يخلون أحدكم بامرأة إلا مع ذي محرم" ((متفق عليه)).
The Messenger of Allah (ﷺ) said, "No one of you should meet a woman in privacy unless she is accompanied by a Mahram (i.e., a relative within the prohibited degrees)."[Al-Bukhari and Muslim].