Hadith number 1287:

وعن ابي هريرة رضي الله عنه قال : قال رسول الله:
<< اذا قاتل احدكم فليجتنب الوجه>>

Narrated Abu Huraira: Allah’s Messenger said, “If any of you fights, he must avoid the face.” (Agreed upon)

Terms:
قاتل (Qatil): means fighting, including both physical (person to person) and in the battle field.

اذا (Itha): IF one fights, he is ordered to stay away from the face. (The Prophet (peace be upon him) put the condition of IF, which means he did not encourage fighting).

Reasons why the Prophet (peace be upon him) deterred from striking the face:

The face is the most beautiful and honorable part of the human body.

The face is also the most sensitive part of the body. If it is hurt, there could be serious repercussions.

Another narration of this hadith states:

وروى مسلم (2612) عَنْ أَبِي هُرَيْرَةَ قَالَ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ
أَخَاهُ فَلْيَجْتَنِبْ الْوَجْهَ فَإِنَّ اللَّهَ خَلَقَ آدَمَ عَلَى صُورَتِهِ إِذَا قَاتَلَ أَحَدُكُمْ

Muslim (2612) narrated that Abu Hurayrah said: The Messenger of Allah (peace and blessings of Allah be upon him) said: “When any one of fights his brother, let him avoid the face, for Allah created Adam in His image.”

There is a difference in opinion in terms of who the “his” refers to, but the strongest is that the pronoun refers to Allah, glorified be He.

Shaykh al-Islam Ibn Taymiyah said: “The word soorah (image) in this hadeeth is like all the other names and attributes narrated (in the texts) where the words used may also be applied to created beings, in a limited manner. When these words are applied to Allah, they carry a unique meaning, such as al-’Aleem (All Knowing), al-Qadeer (All-Powerful), al-Raheem (Most Merciful), al-Samee’ (All Hearing), al-Baseer (All-Seeing), and such as His creating with His hands, rising above the Throne, etc.” Naqd al-Ta’sees, 3/396

What does this hadith mean?

Many groups have interpreted this in different ways:

A. مشبه
They relate human’s attributes to those of Allah’s.

B. تاويل
This is a claim that the pronoun is not referring to Allah, but rather to the fighter.

C. اهل السنة والجماعة (Ahl Sunnah)
There is another hadith where the Prophet (peace be upon him) states the first group to enter Paradise will resemble the moon on a dark night. This example is a figure of speech to show beautiful and how much those particular people will stick out. Similarly, Ka’aba is called الله بيت (House of Allah), this does not mean that Allah lives in Ka’aba. So the above mentioned hadith adds honor to the face.

Based on this hadith, is boxing haram?

Boxing is haram, and this is based on two reasons:
The hadith is very clear in stating it is not permitted to strike the face.
The face is known to be a sensitive part of the body. When it is hit, it can be very serious.

Is wrestling haram?
The answer to this depends if the face is being struck. If not, then this sport is allowable in Islam. There is a hadith where the Prophet (peace be upon him) permitted wrestling. Rikaan, the man who was known to be very good in wrestling, challenged the Prophet to a match. He said if the Prophet won, he would become a Muslim. The Prophet agreed and wrestled the man. The Prophet won. The man asked for another match. Again, the Prophet beat him. So the man became Muslim.

This hadith is used as one of the proofs that niqab (face covering) is wajib.

This hadith teaches that the face is a beautiful and honorable part of the body. The scholars say that if that which is less honorable and beautiful (such as the body) has been ordered to be covered, then what is more beautiful and honored, i.e. face, should be protected and covered the most.

This hadith applies to all types of hitting.

This hadith is applicable to all forms of hitting by everyone, whether it be between a father and his child, a husband and wife, or a Muslim to a kafir.

The humiliation on the face is the worst kind of humiliation.
For disbelievers, most of the torment will be on their faces in the Hell-fire because that would cause them the most disgrace. Allah says in Quran:
يَوْمَ يُسْحَبُونَ فِي النَّارِ عَلَى وُجُوهِهِمْ ذُوقُوا مَسَّ سَقَرَ
“On the day when they are dragged into the Fire upon their faces; taste the touch of Fire. Surely, We have created everything according to a measure” [Surah Al-Qamar: 48]