Assalamualaikum ustaz. What is the ruling of a person who is negligent when performing his ablution that sometimes water isnt wiped properly to all parts of his elbows and heels? 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’ll start with Allah SWT’s statement:
يَا أَيُّهَا الَّذِينَ آمَنُوا إِذَا قُمْتُمْ إِلَى الصَّلَاةِ فَاغْسِلُوا وُجُوهَكُمْ وَأَيْدِيَكُمْ إِلَى الْمَرَافِقِ وَامْسَحُوا بِرُءُوسِكُمْ وَأَرْجُلَكُمْ إِلَى الْكَعْبَيْنِ
“O you who have believed, when you rise to [perform] prayer, wash your faces and your forearms to the elbows and wipe over your heads and wash your feet to the ankles.” 
Al-Maraghi said the meaning of the above verse is if a person wanted to pray – while he is in hadas. The reason is all Muslims agreed that purification (ablution and obligatory bath) is not obligated for a person who wants to pray unless if he is in the state of hadas. 
Wudhuk (ablution) originates from the word wadha’ah (وَضَاءَةٌ). Lexically, it means proper and beautiful. While according to syarak, it is the act of washing certain body parts preceded with the intention. It is named as such because it is an act of bettering and beautifying the body parts washed and cleaned. 
Habib Hasan bin Ahmad al-Kaff stated there are six requisites of ablution. Four of them according to the verses of the Quran are washing the face, both hands, wiping a part of the head and washing both the feet. While two of the remaining requisites based on the sunnah are intention and for the requisites to be performed in order. 
Valid Condition of Ablution
Among the valid conditions of ablution is to not have anything from hindering the water from reaching the skin for the ablution body parts when washing them.  It is also cited in al-Fiqh al-Manhaji  that it is obligatory to wipe the water on all the hair and skin. If there is some dirt under the nails or a person is wearing a ring that prevents the water from reaching the skin, then his ablution is invalid.
This is based on a hadith from Abdullah bin ‘Amr R.Anhuma, he said:
رَجَعْنَا مَعَ رَسُولِ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ مِنْ مَكَّةَ إِلَى الْمَدِينَةِ حَتَّى إِذَا كُنَّا بِمَاءٍ بِالطَّرِيقِ تَعَجَّلَ قَوْمٌ عِنْدَ الْعَصْرِ فَتَوَضَّئُوا وَهُمْ عِجَالٌ فَانْتَهَيْنَا إِلَيْهِمْ وَأَعْقَابُهُمْ تَلُوحُ لَمْ يَمَسَّهَا الْمَاءُ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم: وَيْلٌ لِلأَعْقَابِ مِنَ النَّارِ أَسْبِغُوا الْوُضُوءَ
“We returned from Mecca to Medina with God’s messenger, and when we came to some water on the way some of the people hurriedly performed ablution at the time of the afternoon prayer; but they were too hasty, and when we reached them, their heels were dry, no water having touched them. God’s messenger, therefore, said, “Woe to the heels because of hell! Complete the ablution.” 
Likewise in another hadith, from a narration of Umar bin al-Khattab RA:
أَنَّ رَجُلاً تَوَضَّأَ فَتَرَكَ مَوْضِعَ ظُفُرٍ عَلَى قَدَمِهِ فَأَبْصَرَهُ النَّبِىُّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ فَقَالَ: ارْجِعْ فَأَحْسِنْ وُضُوءَكَ فَرَجَعَ ثُمَّ صَلَّى
“A man was doing wudoo’ for prayer, and he missed an area the size of a fingernail on the top of his foot. The Prophet ﷺ saw him and said: `Go back and do your wudoo’ properly.” So, he went back and did wudoo’ then he prayed.” 
Thus, it is clear a person’s ablution is considered invalid if there is something on the obligatory body parts to be washed but isn’t washed for there is something preventing water, even if it is a little.
The Perfection in Ablution
In this matter, there is a hadith from Nu‘aim bin Abdullah al-Mujmir, he said:
رَأَيْتُ أبا هُرَيْرَةَ يَتَوَضَّأُ فَغَسَلَ وجْهَهُ فأسْبَغَ الوُضُوءَ، ثُمَّ غَسَلَ يَدَهُ اليُمْنى حتّى أشْرَعَ في العَضُدِ، ثُمَّ يَدَهُ اليُسْرى حتّى أشْرَعَ في العَضُدِ، ثُمَّ مَسَحَ رَأْسَهُ، ثُمَّ غَسَلَ رِجْلَهُ اليُمْنى حتّى أشْرَعَ في السّاقِ، ثُمَّ غَسَلَ رِجْلَهُ اليُسْرى حتّى أشْرَعَ في السّاقِ، ثُمَّ قالَ: هَكَذا رَأَيْتُ رَسولَ اللهِ ﷺ يَتَوَضَّأُ. وَقَالَ: قَالَ رَسُولُ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ: أَنْتُمُ الْغُرُّ الْمُحَجَّلُونَ يَوْمَ الْقِيَامَةِ مِنْ إِسْباغِ الْوُضُوءِ، فَمَنِ اسْتَطَاعَ مِنْكمْ فَلْيُطِلْ غُرَّتَهُ وَتَحْجِيلَهُ
“I saw Abu Huraira perform ablution. He washed his face and washed it well. He then washed his right hand including a portion of his arm. He then washed his left hand including a portion of his arm. He then wiped his head. He then washed his right foot including his shank, and then washed his left foot including shank, and then said: This is how I saw Allah’s Messenger (ﷺ) perform his ablution. And (Abu Huraira) added that the Messenger of Allah (ﷺ) had observed: You shall have your faces hands and feet bright on the Day of Resurrection because of your perfect ablution. He who can afford among you, let him increase the brightness of his forehead and that of hands and legs.” 
The word “الْغرَّة” means the white color on the forehead of a horse. While “التَّحْجِيلُ” is the white color on its front and hind legs. It is named the light that will emerge on the ablution body parts in the hereafter with the same white color on the forehead, front and hind legs of a horse as a comparison.  Syeikh Mustafa al-Bugha when commenting on this hadith in Sahih al-Bukhari stated that this hadith means that light will shine from their faces, hands and legs on the Day of Judgement. This is among the advantages granted for this ummah by Allah SWT making it a witness for mankind. 
According to the above arguments and discussion, in our opinion, the ablution of a person is invalid if there is a part of the obligatory ablution body part that wasn’t washed even if the part is a little. The reason is wiping and washing water to all parts of the ablution body parts is one of the valid conditions of ablution.
Moreover, a Muslim should never be negligent when performing ablution, even more so when it results in missing to wash some parts of the obligatory ablution body parts, for there is concern that it may affect other worships that require ablution – when one has to be in a pure state such as prayer, touching or holding the mushaf and others.
Hence, it is prioritized for us to perfect any form of washing or wiping, following the set requisites and order, at the same time performing the sunnah and strive to leave any makruh matters when performing ablution.
May Allah SWT grant us all a clear understanding in this religion. Amin.
 Surah al-Ma’idah: 6
 See Tafsir al-Maraghi, 6/61.
 See al-Fiqh al-Manhaji, 1/53.
 See al-Taqrirat al-Sadidah, pg. 82.
 See al-Mu‘tamad fi al-Fiqh al-Syafi‘i,1/70.
 See al-Fiqh al-Manhaji, 1/55.
 Narrated by Muslim (241)
 Narrated by Muslim (243)
 Narrated by Muslim (246)
 See al-Dibaj ‘ala Sahih Muslim, 2/31
 See Sahih al-Bukhari, 1/39.