The obligatory components (pillars) of wudu are the actions without which it is not valid. Based on the evidence from the Qur'an and Sunnah, Shaykh Ibn 'Uthaymeen explains that there are six essential pillars for wudu.

These are derived directly from the statement of Allah in the Qur'an: "O you who have believed, when you rise to [perform] prayer, wash your faces and your forearms to the elbows and wipe over your heads and wash your feet to the ankles..." (Surah al-Ma'idah, 5:6)

The six pillars are:

1. Washing the Face: This includes the entire face from the hairline to the chin, and from ear to ear. Rinsing the mouth (madmadah) and sniffing water into the nose (istinshaq) are considered part of washing the face and are therefore obligatory.

2. Washing the Arms to the Elbows: The arms must be washed from the fingertips up to and including the elbows.

3. Wiping the Head: This means wiping over the entire head, from the front to the nape of the neck and back to the front. According to the Shaykh, rubbing the ears is also part of wiping the head, as the Prophet (peace and blessings be upon him) said, "The ears are part of the head."

4. Washing the Feet to the Ankles: The feet must be washed thoroughly, including the ankles (the two protruding bones on either side of the joint).

5. At-Tartib (Sequence): The parts must be washed in the specific order mentioned in the verse: face, then arms, then head, then feet. The Prophet Muhammad (peace and blessings be upon him) always performed wudu in this sequence.

6. Al-Muwalat (Continuity): The acts of wudu must be performed consecutively without a long pause between washing one part and the next, such that a limb does not dry completely before the next one is washed (in normal weather conditions).

If any of these six pillars are omitted, the wudu is considered incomplete and invalid.