If one can see the skin under one’s beard, from a normal distance, it would be necessary (wajib) and operationally, obligatory, to wash the skin itself. Otherwise it would be sufficient to wash the hair which covers the skin.
[Shurunbulali, Maraqi al-Falah; Ibn `Abidin, Radd al-Muhtar]
According to the Hanafi school, splashing water on the face, as Imam Shurunbulali (Allah be pleased with him) states in his detailed primer on the Fiqh of Worship, is disliked due to the nobility of the face. Imam Tahtawi (Allah be pleased with him) mentions that the dislikedness applies, similarly, to splashing water on any limb. Imam Shurunbulali (Allah be pleased with him) then goes on to say, explicitly, that one washes one’s face gently.
A Note on Splashing Water and Misgivings
Moreover, the believer acts with dignity and splashing water onto one’s face, or any other limb for that matter, goes against dignified conduct. To consider splashing water on the face as something one must do for the validity of one’s ablution (wudu) would be highly problematic. There is no need for such “caution”. One simply washes one’s face and one has fulfilled one’s duty.
Misgivings are from the devil and come about through ignorance of the sunna of the Beloved of Allah (Allah bless him and give him peace). May Allah give us all the tawfiq to learn and practise the sunna of the Messenger of Allah (Allah bless him and give him peace).
And Allah knows best.