Nasai

Hadith Commentary:
(1)
In one hadith, it is mentioned that the Messenger of Allah (sallallahu alayhi wa sallam) saw a child whose some hair had been shaved and some left unshaven, so he forbade them from this and said:
Shave all of his hair or leave all of his hair.
(Sunan Abi Dawud, al-Tarajjul, Hadith: 4195)
The prohibition is because the priests and monks of the People of the Book used to do this, and it was the way of sinful people. Moreover, this style gives an impression of deformity in creation.
(Fath al-Bari: 10/448)
(2)
In the present era, hair is kept on the head while the neck is shaved clean, and then the hair gradually increases in length above the neck. Especially, the hair of soldiers and police officers is cut in this manner, which is called a "military cut."
This method also resembles "qaza‘" (partial shaving), so one should avoid this style as well.
Nowadays, under the name "burger cut," half or less than half of the head is shaved, which also falls under the prohibition of qaza‘.
(3)
In any case, Muslims should always avoid imitating the polytheists and disbelievers.
We should promote and adopt Islamic culture in clothing and hairdressing.
The youth of Islam should strive against such wrong traditions; especially, there is absolutely no allowance in Islam for keeping hair in the style of "hippie-ism."
And Allah knows best.

Hadith Commentary: Leaving patches of hair is called "qaza‘".

Benefits and Issues:
Among the people of innovation (ahl al-bid‘ah), it is customary that they do not cut some hair in the name of certain pirs and elders, leaving one lock remaining. This action of theirs is forbidden (haram), because it is an act of dedicating (nazr) to other than Allah.

Benefits and Issues:
Nowadays, what is done among us under the name of "burger cut," in which half of the head is shaved, is not permissible in light of this hadith.

Urdu marginal note:
By "qaza‘" is meant that the head is shaved in some places and left unshaven in others. For the reason for its prohibition, see Hadith number 5051.

This narration, with these words, is rejected (munkar). The attribution of this narration to al-Bukhari and Muslim by the editor of the book is not correct, because the context (siyaq) of al-Bukhari and Muslim is according to the following narration. See: (Dhakheerat al-‘Uqba Sharh Sunan al-Nasa’i: 38/13)

Commentary:
Benefits and Issues:

➊ (Qaza‘)
The literal meaning is: scattered pieces of cloud.
In the hadith, its meaning is exactly as explained by Ibn ‘Umar (radi Allahu anhu).

➋
The reason for its prohibition has been stated as that the priests and monks of the People of the Book used to do this.
Another reason is that this was the practice of sinful people.

➌
Nowadays, people keep long hair on the head and shave it clean from the nape of the neck.
And from the nape, the hair gradually becomes longer.
Especially, the particular style of cutting the hair of soldiers and police officers also resembles this, in which most of the hair is cut.
This method is, in one respect, similar to qaza‘ and is contrary to the Shari‘ah, so it should be avoided.

➍
If, due to some illness or another valid excuse, it becomes necessary to shave the hair from a part of the head, then it is permissible.