Four Fara’id of Ablution[1]

Washing the face
Washing both forearms including the elbows
Wiping a quarter of the head
Washing both feet including the ankles
Definition of Washing

It is stated in Marāqī al-Falāh:

Washing a limb entails that at least 2 drops of water must flow over that limb. If the limb is simply moistened by rubbing a wet hand over it, or if only 1 drop of water flows over it then it will not be considered washed and the ablution or ghusl will not be considered complete.[2]

[1] Imām Abū Hanīfa, Sahīfa

Fatāwah Alamgīrī, vol. 1, pp. 3

[2] Marāqī al-Falāh, pp. 57

Imām Aḥmad RiĎā al-Qādrī, al-Atāya Nabawīyyah fil Fatāwah Ridhwīyyah, vol. 1 pp. 218. Rida Foundation