Is washing the skin underneath the beard hair obligatory if the beard is dense?
Chapter on Siwak and the Sunnah of Wudu
Al-Mughni
Book of Purification
Primary text
If the beard skin is visible, washing its interior is obligatory. If the beard hair is dense, washing what is underneath it is not obligatory. However, rubbing through the beard hair (Takhleel) is recommended. Ibn Umar, Ibn Abbas, Al-Hasan, Anas, Ibn Abi Layla, and Attab as-Sa'ib narrated that they used to rub through their beards. Ishaq held that intentionally omitting the rubbing of the beard necessitates repeating the Wudu because the Prophet, peace be upon him, used to rub through his beard. This hadith, narrated by Uthman ibn Affan, is considered Hasan Sahih by Al-Tirmidhi and the soundest hadith in the chapter by Al-Bukhari. Anas narrated that the Prophet used to take a handful of water and draw it under his chin, saying, "This is how my Lord commanded me." Ibn Umar narrated that the Prophet used to rub his jaws with some rubbing and intertwine his beard fingers from underneath.
Supporting text
Ata and Abu Thawr hold that washing the interior of the face hair is obligatory even if dense, just as it is obligatory in Ghusl (major ritual bath), based on the shared command to wash the face in both. The majority of scholars rule that it is not obligatory, nor is rubbing through the beard required. Those who permit omitting the rubbing include Ibn Umar, Al-Hasan ibn Ali, Tawus, Al-Nakha'i, Al-Sha'bi, Abu Al-'Aliyah, Mujahid, Abu Al-Qasim, Muhammad ibn Ali, Sa'id ibn Abd al-Aziz, and Ibn al-Mundhir. Their evidence is that God commanded washing but did not mention rubbing, and most narrators of the Prophet's Wudu did not mention it; had it been obligatory, they would have mentioned it, or if performed always, most narrators would have reported it. Its omission indicates that washing underneath dense hair is not obligatory, as the Prophet had a dense beard, and water would not reach underneath without rubbing; performing it sometimes indicates recommendation, not obligation.