Do young girls have to wear hijaab?

Question: What is the ruling concerning the young girls who have not reached the age of puberty? Is it allowed for them to go out without covering themselves? Can they pray without wearing a head covering?

Response: It is a must that their guardians bring them up and teach them the manners of Islaam. They should tell them not to go outside unless their bodies are covered. This is in order to avoid any temptation and to get them used to the virtuous manners so that they will not be a source of spreading evil. They should be ordered to pray with head coverings. If they pray without it, their prayers are sound. This is because the Prophet (sal-Allaahu `alayhe wa sallam) said, ((Allaah does not accept the prayer of a female who has reached the age of puberty except if she is wearing a head covering (khimaar).)) This was recorded by at-Tirmidhee, Ahmad, Abu Daawood and Ibn Maajah.
And with Allaah lies all success and may Allaah send prayers and salutations upon our Prophet (sal-Allaahu `alayhe wa sallam) and his family and his companions.

The Permanent Committee for Islaamic Research and Fataawa
Fataawa al-Mar.ah

Q. My brother dresses his four year old daughter in a veil and says, “He who grows up upon something grows old upon it”, and he tries to force this upon my children. Whereas I disagree with him in this, and say to him, when they reach their menses. What is your opinion about this severity by which he has chained the childhood of this child at the age of four? May Allah reward you with good.

A. There is no doubt that your brother’s statement is the common occurrence: He who grows up upon something grows old upon it, this is why the Prophet, salallahu ‘alayhi wa salam, has ordered the one who reaches the age of seven years to perform the prayer, even though he is not yet responsible for his actions, rather this is an order than he be accustomed to it.
As for a young girl, there is no ruling concerning her private zone, it is not obligatory upon her to cover her face, neck and hands or feet, and it is not befitting that she be forced into this. Whereas if she reaches a stage at which men start to become attracted to her, then she should wear the hijab to prevent trials and evil. This varies with different women, for there are some who develop quite rapidly, while others are the opposite of this. Allah is the One Who gives success.

Shaykh Ibn ‘Uthaymeen
[Fataawa Manaar al-Islaam: 3/810]
(also found in Islamic Fataawa Regarding the Muslim Child, page 153)