Musnad Ishaq

Benefits:
From the mentioned hadith, it is understood that washing the feet in ablution (wudu) is obligatory, and this hadith also refutes those who hold the view of merely wiping (masah) over the feet, whereas there is no wiping over the feet; rather, it is obligatory to wash the feet thoroughly. Wiping (masah) is only permissible when socks (khuffayn) or stockings are worn in a state of ablution, or if there is a wound on the feet and there is a risk of harm from water.

It is also understood that an incomplete ablution (wudu) is a cause of destruction. Furthermore, it is understood that even a believer, due to some sin, can become deserving of the punishment of Hellfire, but this will not be an eternal punishment. It is also evident that an incomplete ablution is not acceptable; therefore, one should perform ablution properly.

In another hadith, it is narrated that Sayyiduna Anas radi Allahu anhu reports: The Noble Prophet sallallahu alayhi wa sallam saw a man in whose foot there was a spot the size of a fingernail where water had not reached. So the Prophet sallallahu alayhi wa sallam said: "Go back and perform ablution well." (Sunan Abu Dawud, No. 173; Sunan Ibn Majah, No. 665)