Sahih Ibn Khuzaymah

And the explanation of the evidence that Allah Almighty makes a certain obligation mandatory in the Holy Qur’an in one sense, and then makes the same obligation mandatory in another sense through the tongue of His Prophet (peace be upon him). According to the command of Allah Almighty in the Holy Qur’an, defecation and sexual intercourse with women make ablution obligatory, because Allah Almighty has commanded the sick and the traveler to perform tayammum after defecation and sexual intercourse with women in the absence of water. Therefore, according to the command of the Book of Allah, a healthy person, in the presence of water, must perform ablution after defecation and sexual intercourse with women, because tayammum with pure earth has been made a substitute for ablution for the traveler and the sick in the absence of water. And the Noble Prophet (peace be upon him) informed that ablution becomes obligatory due to things other than defecation and sexual intercourse with women. In the narration of Sayyiduna Safwan bin Assal (may Allah be pleased with him), the Noble Prophet (peace be upon him) stated that each of urination and sleep makes ablution obligatory, even though the one who urinates and the one who sleeps are other than the one who defecates and the one who has sexual intercourse with women. Soon, with the will and help of Allah Almighty, I will mention such events that make ablution obligatory, which are established by the command of the Prophet (peace be upon him), and those are other than the events mentioned in the Holy Qur’an, i.e., other than defecation and sexual intercourse with women. Contrary to the statement of that person, who is not a reliable scholar, who says that it is not permissible for Allah Almighty to mention a command in the Holy Qur’an and make it conditionally obligatory, and then the same command becomes obligatory without the condition mentioned in the Holy Qur’an.

Zirr bin Hubaish (may Allah have mercy on him) says that I went to the service of Sayyiduna Safwan bin Assal Muradi (may Allah be pleased with him) to inquire about wiping over the socks. He asked, "O Zirr, what brings you here?" I said, "I have come in search of knowledge." He said, "O Zirr, indeed the angels spread their wings in approval and happiness for the seeker of knowledge in his quest and pursuit of knowledge." He said, "I said, 'After relieving oneself, I have some doubt in my heart regarding wiping over the socks, and you are a companion of the Messenger of Allah (peace and blessings be upon him). Have you heard the Messenger of Allah (peace and blessings be upon him) say anything about this?'" He said, "Yes (I have heard). The Messenger of Allah (peace and blessings be upon him) used to command us that when we are travelers, except in the case of major impurity (janabah), we should not remove our socks for three days and nights. There is no need to remove them because of defecation, urination, or sleep." This is the narration of Makhzumi. In the narration of Ahmad bin Abda, it is: "This hadith has reached me that the angels spread their wings."