Najis comes from the word of najasah that means dirt. In the book of Ar Raudhatun Nadiyyah (1/12), it is explained that,
النجاسات جمع نجاسة, و هي كل شيئ يستقذره أهل الطبائع السليمة و يتحفظون عنه و يغسلون الثياب إذا أصابهم كالعذرة و البول
“Najasat is the plural form of najasah, it is everything that is considered to be dirty by people that have a clean fitra and they will try to avoid it and clean their clothes if it is exposed to it such as human feces or urine.”
وَعَهِدْنَا إِلَى إِبْرَاهِيمَ وَإِسْمَاعِيلَ أَن طَهِّرَا بَيْتِيَ لِلطَّائِفِينَ وَالْعَاكِفِينَ وَالرُّكَّعِ السُّجُودِ
“And we order Ibrahim and Ismail to purify My house for people who do tawaf, i’tikaf and people who bow and prostrate.” (QS. Al-Baqarah: 125)
It is also the same in a story of the Prophet that told a threat for people who do not want to purify during their lives.
From Ibnu Abbas radhiallahu’anhu, the Prophet shallallahu ‘alaihi wa sallam said:
مَرَّ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَلَى قَبْرَيْنِ فَقَالَ أَمَا إِنَّهُمَا لَيُعَذَّبَانِ وَمَا يُعَذَّبَانِ فِي كَبِيرٍ أَمَّا أَحَدُهُمَا فَكَانَ يَمْشِي بِالنَّمِيمَةِ وَأَمَّا الآخَرُ فَكَانَ لا يَسْتَتِرُ مِنْ بَوْلِهِ
“The Prophet shallallahu ‘alaihi wa sallam passed through two graves. Then he said, “these two people are being punished, and they are not punished because of a major sin. The first one is punished because of doing namimah (to pit against someone). There is also the second one, he is punished because he did not clean himself from his remaining urine.”” (Hadith Muslim no. 292)
In Islam, there are 3 groups of impure which the ways to purify them are also different. The following is a brief explanation about the ways to clean impure in Islam.
This impure is a heavy impure that must be cleaned with a specific way. How to clean it combines the water and soil with a certain amount and procedure. The way is by washing or rinsing the part that is exposed to impure with the water that is mixed with soil on the first wash and the next is with the plain water. The washing must also be done for seven times. This is in accordance with the words of the Prophet,
طَهُورُ إِنَاءِ أَحَدِكُمْ إِذَا وَلَغَ فِيهِ الْكَلْبُ، أَنْ يَغْسِلَهُ سَبْعَ مَرَّاتٍ أُولَاهُنَّ بِالتُّرَابِ
“How to purify a container of the one among you if it is licked by a dog is by washing it seven times, the first wash is with soil.” (Hadith Al-Bukhari no. 182, Muslim no. 279)
There are also those that belong to this impure, they are dogs and pigs. If there is a dog licking clothes or stuffs, then we must purify it as the way above. Meanwhile, if it licks the food that is solid and frozen, then the part of food that is exposed to it must be thrown away, and the rest of the food can be eaten because it is not exposed to it and is still pure. However, if the dog licks the water in a container, then all of the water must be thrown away.
This impure is purified by three different ways according to its types. To more easily to understand it, the following is a brief explanation about it:
1. By splashing water
One of the types of najis mukhaffafah is the urine of a baby who has not eaten. How to purify or clean it is only by splashing water.
From Abu Samh Malik radhiallahu’anhu, he said:
يُغْسَلُ مِنْ بَوْلِ الْجَارِيَةِ وَيُرَشُّ مِنْ بَوْلِ الْغُلاَمِ
“The urine of a girl is washed, while the urine of a boy is splashed.” (Hadith Abu Daud 377, An Nasa’i 303, were validated by Al Albani in Shahih An Nasa’i)
Besides the urine of a baby that has not eaten, there is also madzi that is allowed to be purified by only splashing water.
Ali bin Abi Thalib radhiallahu’anhu, he said:
أرسَلْنا المِقْدَّادَ بنَ الأسودٍ إلى رسولِ اللهِ صلى الله عليه وسلم ،فسألَه عن المَذْيِ يَخْرُجُ مِنَ الإنسانِ كيفَ يَفْعَلُ به ؟ فقال رسولُ اللهِ صلى الله عليه وسلم : تَوَضَّأْ ،وانْضَّحْ فَرْجَكَ
“Miqdad bin Al Aswad sent me to the Prophet shallallahu ‘alaihi wa sallam. Then I asked about madzi that came out from someone, how to overcome it? Then the Prophet shallallahu ‘alaihi wa sallam said: ‘Wudu’ and splash your genital with water.'” (Hadith Muslim 303)
2. It is enough to flush once or the object disappears
Such the treatment is done on impure that is on the floor. It is the same as what happened in the Prophet era.
From Anas bin Malik radhiallahu’anhu, he said:
جَاءَ أَعْرَابِيٌّ فَبَالَ فِي طَائِفَةِ المَسْجِدِ، فَزَجَرَهُ النَّاسُ، «فَنَهَاهُمُ النَّبِيُّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ فَلَمَّا قَضَى بَوْلَهُ أَمَرَ النَّبِيُّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ بِذَنُوبٍ مِنْ مَاءٍ فَأُهْرِيقَ عَلَيْهِ»
“A Bedouin urinated in one part of the mosque, then people wanted to scold him. However, the Prophet shallallahu ‘alaihi wa sallam forbidden them to scold him. When he finished urinating, the Prophet shallallahu ‘alaihi wa sallam ordered to flush his urine with a bucket of water.” (Hadith Al-Bukhari no. 221, Muslim no. 284)
3. Touch to the ground
How to purify this one is done on slippers or clothes that are exposed to impure on the ground. We do not need to change the robe that may be dragged while walking on the ground because the robe has been purified by the ground afterwards.
From Ummu Salamah radhiallahu’anhu. From the way of Ummu Walad (it is also called: Hamidah), said:
قُلْتُ لأُمِّ سَلَمَةَ: إِنِّي امْرَأَةٌ أُطِيلُ ذَيْلِي وَأَمْشِي فِي الْمَكَانِ القَذِرِ؟ فَقَالَتْ: قَالَ رَسُولُ اللهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: يُطَهِّرُهُ مَا بَعْدَهُ
“I asked Ummu Salamah: ‘I am a woman that has a long dress and I usually walk in a dirty place’. Ummu salamah said: ‘The Prophet shallallahu ‘alaihi wa sallam said: ‘the ground afterwards has cleaned it.'” (Hadith Tirmidzi 143, he said: “this hadith is valid”)
This impure is the impure that belongs to blood, feces, a carrion, and others which must be cleaned until the form, color, and smell disappears. Syaikh As Sa’di explained:
“When najasah (mutawashitah) can disappear in any way, and with any tool, then it has enough to purify it. Without the required amount and does not have to use water. This is shown by zhahir nash verses. Because the sharia in this only orders to remove the impure. And that impure sometimes disappears by using water, sometimes by washing it, sometimes by istijmar (using stone, wood or something like that), and sometimes by other ways. And the sharia does not order to remove the impure seven times, except impure dogs. As this opinion is also a common from the nash of shar’i verses, because this opinion has a high suitability with nash. Because that impure removal is a removal that is mahsuusah (can be sensed).” (Irsyad Ulil Bashair wal Albab li Nailil Fiqhi, 21)
Those were some brief explanations about 3 ways to clean impure in Islam.