Is Wiping Part of the Head Enough in Wudu?
Question

Is it possible when doing Wudu to wipe a small part of the head at the back and not at the front?
Praise be to Allah.Is wiping the hair mandatory in Wudu?
The Muslims unanimously agreed that it is obligatory to wipe the head when doing Wudu, because Allah Says (interpretation of the meaning):
{O you who believe! When you intend to offer the prayer, wash your faces and your hands (forearms) up to the elbows, rub (by passing wet hands over) your heads, and (wash) your feet up to the ankles.} [Al-Ma’idah 5:6]
Is Wiping Part of the Head Enough in Wudu?
The jurists agreed that it is best to wipe the entire head, but they differed as to whether doing so is obligatory or not. The Malikis and Hanbalis are of the view that it is obligatory to wipe the entire head. The Hanafis and Shafi`is are of the view that it is sufficient to wipe part of the head.
The Malikis and Hanbalis quoted a number of things as evidence:

Allah Says (interpretation of the meaning): {rub (by passing wet hands over) your heads} which includes the entire head.

This verse – “rub (by passing wet hands over) your heads” – refers to the entire head and it is like the phrase in which Allah says concerning Tayammum (interpretation of the meaning): {then perform Tayammum with clean earth and rub therewith your faces and hands.} [Al-Ma’idah 5:6] The entire face must be wiped in Tayammum, and the same applies to the head in this case. (End quote from Majmu’ Al-Fatawa, 21/125)
Ibn `Abd Al-Barr (may Allah have mercy on him) said:
The jurists differed concerning the one who wipes part of the head. Malik said: What must be done is to wipe the entire head, and if he omits part of it then he is like one who fails to wash part of his face. This is the well-known view in the Madhhab of Malik, and it is also the view of Ibn `Uliyyah. Ibn `Uliyyah (may Allah have mercy on him) said: Allah commanded us to wipe the head in Wudu as He commanded us to wipe the face in Tayammum and to wash it in Wudu. They unanimously agreed that it is not permissible to wash only part of the face in Wudu or to wipe only part of it in Tayammum. The same applies to wiping the head. (End quote from At-Tamhid, 20/114)

They quoted as evidence the actions of the Prophet (peace and blessings of Allah be upon him), for there is a proven report of him wiping only part of his head.

The Hanafis and Shafi`is also quoted evidence, including the following:

Allah says (interpretation of the meaning): {rub (by passing wet hands over) your heads [wa’msahu bi ru’usikum]} – the Ba’ (before the word ru’usikum (heads)) indicates something partial, as if He were saying: “Wash part of your heads.”

My response to that is to note that the Ba’ does not indicate something partial, rather it refers to making something stick, i.e., it is obligatory to make some of the water with which one is wiping the head stick to the head. (End quote from Majmu` Al-Fatawa, 21/123)

The report narrated by Muslim (247) from Al-Mughirah ibn Shu`bah (may Allah be pleased with him) who said that the Prophet (peace and blessings of Allah be upon him) wiped his forelock and his turban. They said: He (peace and blessings of Allah be upon him) only wiped the forelock, which is at the front of the head.

The response to that is that he (peace and blessings of Allah be upon him) wiped his forelock and completed the wiping over his turban, and wiping the turban took the place of wiping over the head.
Ibn Al-Qayyim (may Allah have mercy on him) said in Zad Al-Ma`ad (1/193): There is no sound report in a single Hadith that the Prophet (peace and blessings of Allah be upon him) ever wiped over only part of his head. But if he wiped over his forelock, he completed the wiping by wiping over his turban. (End quote)
Shaykh Ibn `Uthaymin (may Allah have mercy on him) said: Wiping over the forelock was sufficient here because he also wiped over the turban at the same time. So this does not indicate that it is permissible to wipe over the forelock only. (End quote from Ash-Sharh Al-Mumti`, 1/178)
Thus it seems that the more correct of the two views is the view that it is obligatory to wipe over the entire head when doing Wudu.
It says in Fatawa Al-Lajnah Ad-Da’imah (5/227):
It is obligatory to wipe over the entire head when doing Wudu, because Allah Says “rub (by passing wet hands over) your heads”, and because of the report narrated by Al-Bukhari and Muslim from `Abdullah ibn Zayd ibn `Asim (may Allah be pleased with him) describing Wudu, in which he said: “The Messenger of Allah (peace and blessings of Allah be upon him) wiped his head, moving his hands forwards and backwards.” According to another version: “He started at the front of his head until he moved them (his hands) to the back, then he brought them back to the place where he had started.” (End quote)
Shaykh Ibn `Uthaymin (may Allah have mercy on him) said in Ash-Sharh Al-Mumti` (1/187): If he wipes the forelock only and not the rest of the head, that is not sufficient, because Allah says: “rub (by passing wet hands over) your heads.” [Al-Ma’idah 5:6] And He did not say, “part of your heads.” (End quote)
And Allah knows best.