Hadith: This fire is your enemy, so put it out before going to bed

عن أبي موسى الأشعري رضي الله عنه قال: احْتَرَقَ بَيْتٌ بالمَدِينَةِ عَلَى أهْلِهِ مِنَ اللَّيْلِ، فَلَمَّا حُدِّثَ رَسُولُ اللهِ صلى الله عليه وسلم بِشَأنِهِم، قالَ: «إنَّ هذه النارَ عَدُوٌّ لَكُمْ، فَإِذَا نِمْتُم، فَأَطْفِئُوهَا عَنْكُمْ».
[صحيح] - [متفق عليه]

Abu Mūsa al-Ash‘ari (may Allah be pleased with him) reported: One night, a house in Madīnah was burnt with its inhabitants inside. When this was reported to the Messenger of Allah (may Allah's peace and blessings be upon him) he said: “This fire is your enemy, so put it out before going to bed."
Sahih/Authentic. - [Al-Bukhari and Muslim]

Explanation

A house in Madīnah was burnt one night, and the Prophet (may Allah's peace and blessings be upon him) heard about it. So, he informed people that this fire is their enemy if they do not take precautions against its flames and burning effect. Then, he ordered them to put it out before sleeping so as to avoid its outbreak.