Al-Ahzab · 33:32

32. O the wives of the Prophet (peace be upon him), You are not like other women in terms of privilege and nobility; you are on a level of privilege and nobility other women can never reach even if they were to fulfil the commands of Allah and refrain from things He has not allowed. Therefore, do not soften your tone when you speak to unrelated men, in case those with the disease of hypocrisy or impermissible desires begin to lust. Rather, speak in a manner well clear of any doubt, by speaking in a serious and not trivial tone as necessary.