I know that a woman must cover her hair when praying. I try to cover it the best I can before I pray. However, sometimes a short hair slips out while praying, that I usually notice afterwards. I am wondering if I have to repeat my prayer again. I have been repeating the prayers, but it is making praying very cumbersome (esp. because I have small children). Do I need to repeat the prayer if even a single short hair slips out of my hijab while praying?
Thank you for answering.

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

If some of the woman's hair is disclosed during the prayer this does not make her prayer void if she covers it quickly.

Ibn – Qudama said in Al – Mughni: "If the awra of a woman's hair is disclosed and she covers it on the spot without delay then this does not make the prayer invalid.

The woman's hair is a part of her Awrah and it is not permissible for her to disclose it during the prayer. The Maliki School of thought are of the opinion that it is desirable for the woman to repeat her prayer immediately, if her head is revealed or some of her limbs.

The combined text  of Al – Dardir and Khalil Ibn Ishaq said: "the free woman should repeat her prayer for exposing her bosom or limbs, like neck, head, arms or her heels if they are exposed partly or wholly. The same thing applies to the back which is the part opposite the bosom, if exposed for a period (during the prayer)."

However, if the time of the prayer has expired, it is not desirable to repeat the prayer according to them.

The conclusion is that you are not required to repeat the prayer according to the situation that you described. Nevertheless, it is desirable for you to repeat it according to the Maliki school of thought if the time of the prayer has not expired.

You have to know that the obligation of covering the hair for a woman is not only during the prayer, but it is an obligation on her during the prayer and outside the prayer if she is in a place where she can be seen by alien man (a non- Mahram).

Allah knows best.