Assalamualaikum ustaz. What is the ruling if we use the refrigerator and cooking utensils left by non-Muslims, for there is a possibility that they kept champagne and pork in the fridge or cooked non-halal food with their cooking utensils? Hope for an explanation.
Waalaikumussalam wrt. wbt.,
Alhamdulillah, praise and gratitude to Allah SWT for His countless blessings for us all. Praise and salutations to our beloved Prophet Muhammad PBUH, his family, companions, and all those who follow his footsteps until the Final day.
We start with the statement of Allah SWT:
أَوْ لَحْمَ خِنزِيرٍ فَإِنَّهُ رِجْسٌ
“Or the flesh of swine – for indeed, it is impure.”
Dr Wahbah al-Zuhaili stated that the prohibition of swine includes all parts of the animal including its fats and skin. However, its flesh is specified because it is its main purpose – that is to be eaten. Indeed, Syarak prohibits benefitting from any part of the swine according to the above verse. 
Basically, it is impermissible for us to use any cooking utensils or pots that have been used to cook najis in them – such as meat that is slaughtered not following the syarak, wine and others – except after they are purified and cleaned beforehand. This is based on a hadith narrated by Abu Tha’labah al-Khusyani, where he asked Rasullullah PBUH:
يَا نَبِيَّ اللَّهِ، إِنَّا بِأَرْضِ قَوْمٍ مِنْ أَهْلِ الكِتَابِ، أَفَنَأْكُلُ فِي آنِيَتِهِمْ؟ قَالَ: أَمَّا مَا ذَكَرْتَ مِنْ أَهْلِ الكِتَابِ، فَإِنْ وَجَدْتُمْ غَيْرَهَا فَلاَ تَأْكُلُوا فِيهَا، وَإِنْ لَمْ تَجِدُوا فَاغْسِلُوهَا وَكُلُوا فِيهَا
“Prophet of God, we are in a land belonging to folk who are people of the Book, so may we eat out of their vessels?” He replied, “Regarding what you have mentioned about the vessels of the people of the Book, if you can get anything else do not eat out of them, but if you cannot, wash them and eat out of them.” 
Scholars stated that this hadith can be understood to mean that the containers have been used to cook and drink najis as clearly stated in another narration of Abu Tha’labah, he said:
إِنَّا نُجَاوِرُ أَهْلَ الْكِتَابِ، وَهُمْ يَطْبُخُونَ فِي قُدُورِهِمْ الْخِنْزِيرَ، وَيَشْرَبُونَ فِي آنِيَتِهِمْ الْخَمْرَ؟ فَقَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: إِنْ وَجَدْتُمْ غَيْرَهَا، فَكُلُوا فِيهَا وَاشْرَبُوا، وَإِنْ لَمْ تَجِدُوا غَيْرَهَا فَارْحَضُوهَا بِالْمَاءِ وَكُلُوا وَاشْرَبُوا
“We live in the neighbourhood of the People of the Book and they cook in their pots (the flesh of) swine and drink wine in their vessels. The Messenger of Allah(ﷺ) said: If you find any other pots, then eat in them and drink. But if you do not find any others, then wash them with water and eat and drink (In them).” 
Al-Khattabi said the original ruling in this matter, if it is a known fact that the non-Muslims cooked pork in their pots and drink wine in their glasses, then it is impermissible to use their utensils except after first they are washed and cleaned.
Furthermore, Imam al-Nawawi commented that the statement of al-Syirazi who holds the opinion that it is makruh to use the containers of non-Muslims and wear to use their clothes, regardless of whether they are the People of the Book or others, or whether they use najis in their religious practice or others means that one is uncertain as to the cleanliness of the containers and clothes. The reason is if one is sure and certain of the cleanliness of the containers and clothes, then scholars of madhhab Syafie are of the opinion that it is no longer makruh to wear them, the same as the clothing of another Muslim. Among the scholars who explained this matter are al-Mahamili in al-Majmu‘, al-Bandaniji, al-Jurjani in al-Bulghah, al-Baghawi, the authors of al-‘Uddah and al-Bayan and others and we don’t know of any difference of opinions in this issue.
Next, Imam al-Nawawi further stated, that when a person perform purification using containers of a non-Muslim and he doesn’t know if the container is pure or najis. In this matter, if the non-Muslim is from those who don’t use najis in their religious practice, then purification using such a container is valid without any khilaf. If the non-Muslim is from those who use najis in their religious practice, then there are two opinions. The sahih opinion with the agreement of the Ashab (scholars of madhhab Syafi’i) is at two routes that are the purification is valid and this is from Imam al-Syafi’I in al-Umm, Harmalah and the Qadim opinion. This is also the opinion of Ibn Abi Hurairah. While the second opinion states that the purification is invalid and this is the opinion of Abu Ishaq and stated as sahih – which means it is chosen – by al-Mutawalli. 
Furthermore, Dr Muhammad al-Zuhaili stated the permissibility of using the containers and clothes of non-Muslims is based on the hadith by Abu Tha’labah. While the commandment to wash them is sunnah, for non-Muslims usually don’t keep themselves away from najis. Likewise, it is permissible to perform ablution using their containers, if they aren’t from among those who use najis in their religious practises. However, if they are from those who use najis in their religious practises such as the Majus and Brahmin who bathe using cow’s urine as a way to get closer to god, then ablution using their containers is valid but makruh, for the original ruling is pure. 
Moreover, in al-Fiqh al-Manhaji it is stated that the commandment to wash containers is sunnah because there is a possibility that it may be impure because non-Muslims have used them to drink wine, eat pork and others. Likewise, the ruling of wearing their clothes is the same as the ruling of using their containers.
According to the above discussion and arguments, in our opinion, it is permissible to use the refrigerator or other utensils owned by non-Muslims for the original ruling for them is that they are pure and clean unless there is evidence that proves otherwise. In this matter, there is an Islamic legal maxim which states:
نَحْنُ نَحْكُمُ بِالظَّاهِرِ، وَاللهُ يَتَوَلَّى السَّرَائِرَ
“We decide on a ruling based on what is apparent and Allah will manage what is hidden.” 
However, if there are other pots or utensils that can be used – other than the ones owned by non-Muslims – then it is prioritized to use them first. Likewise, it is sunnah for us – and this is not an obligation – to wash or clean them first with water, for najis may have been left by the previous non-Muslims who used them.
However, if it is clear that there is najis or strong evidence that proves this, then it is obligatory to first wash and purify the containers or utensils from the najis before using them. If it is in the mutawassitah (moderate) najis category, then wash them using mutlak water. If it is from the mughallazah (major) najis, then according to madhhab Syafi’I, it should be washed seven times with mutlak water and once with water mixed with soil.
May Allah SWT grant us all a clear understanding in this religion. Amin.
 Surah al-An‘am: 145
 See al-Tafsir al-Munir, 6/77.
 Narrated by al-Bukhari (5478)
 Narrated by Abu Daud (3839)
 See Ma‘alim al-Sunan, 4/257.
 See Majmu‘ Syarh al-Muhazzab, 1/263-264.
 See al-Mu‘tamad fi al-Fiqh al-Syafi‘i, 1/50-51.
 See al-Fiqh al-Manhaji, 1/37.
 See al-Tafsir al-Munir, 9/324.