Sayyiduna Sa’d bin Hisham narrates that I came to Hazrat Hakim bin Aflah, then we went to the service of Sayyidah Aisha (may Allah be pleased with her). We sought permission, and we were granted permission to be present. We said,“O Mother of the Believers, tell me about the noble character of the Messenger of Allah (peace and blessings be upon him).”She replied,“Do you not recite the Qur’an?”She meant the saying of Allah Almighty: «‏‏‏‏وَإِنَّكَ لَعَلَىٰ خُلُقٍ عَظِيمٍ» ‏‏‏‏ [ سورہ القلم: 4 ] “Indeed, you are upon a great character.”He said,“Why not, (I do recite this verse).”The Mother of the Believers said,“Indeed, the character of the Messenger of Allah (peace and blessings be upon him) was the Qur’an itself.”Then I said,“O Mother of the Believers, inform me about the night prayer (Qiyam) of the Messenger of Allah (peace and blessings be upon him).”She said,“Do you not recite Surah Al-Muzzammil?”He says,“I said, ‘Yes, I do.’”Then she said,“Indeed, Allah Almighty made standing in the night obligatory at the beginning of this Surah. So the Prophet of Allah and his noble companions stood in prayer at night for a year until their feet swelled. And Allah Almighty kept the last part of this Surah withheld in the heavens for twelve months. Then Allah Almighty revealed ease at the end of this Surah. Thus, after being obligatory, standing at night became voluntary.”Then she narrated the rest of the hadith. At the end of the hadith are these words:“So I went to the service of Sayyiduna Ibn Abbas (may Allah be pleased with them both) and related to him the conversation of the Mother of the Believers. He said, ‘(Our mother) has spoken the truth.’”

And it is also permissible that a voluntary act (nafl) be abrogated and made obligatory again, just as in the beginning it was obligatory.

Lady Aisha (may Allah be pleased with her) narrates that the Messenger of Allah (peace and blessings be upon him) went from home to the mosque at midnight and performed (Tahajjud) prayer. Some people also prayed with him. In the morning, people informed each other about this. Then, when the third night came, many people gathered in the mosque. The Prophet (peace and blessings be upon him) came and they performed prayer with him. Then, when the fourth night came, the mosque could not accommodate all the people, and the Messenger of Allah (peace and blessings be upon him) did not come to them. Some of them kept calling out, "Prayer, prayer," to the Prophet (peace and blessings be upon him), but the Messenger of Allah (peace and blessings be upon him) did not come out. This continued until he came out for the Fajr prayer. Then, when the Prophet (peace and blessings be upon him) completed the Fajr prayer, he stood up, turned his blessed face towards the people, delivered a sermon, praised and glorified Allah Almighty, and then said: "As for what follows, indeed your situation (attendance) was not hidden from me, but I feared that the night prayer might be made obligatory upon you, and then you would be unable to perform it." These are the words of the narration of Al-Durqutni.

Sayyiduna Abdullah bin Amr bin al-As (may Allah be pleased with him) narrates that the Messenger of Allah (peace be upon him) said: "Do not become like such-and-such person; he used to stand (in prayer) at night, then he abandoned the night prayer." In the narration of Yunus, these words are mentioned: The Messenger of Allah (peace be upon him) said: "O Abdullah, do not be like (such-and-such person)."

It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that a man came to the Noble Prophet (peace and blessings be upon him) and said, "Indeed, so-and-so slept through the night and did not pray." The Messenger of Allah (peace and blessings be upon him) said: "Satan has urinated in that man's ear or both his ears (that is why he remained in a deep sleep until morning)." These are the words of Abu Musa's hadith.

Because of the knots of Satan being untied, he becomes energetic and cheerful in the morning.

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates from the Prophet (peace and blessings of Allah be upon him) in a marfu’ report that he (peace be upon him) said:“The Shaytan ties three knots at the back of the head of any one of you when he sleeps. On each knot he breathes the following words: ‘You have a long night ahead, so sleep.’ If he wakes up and remembers Allah, one knot is undone. If he performs ablution, two knots are undone. Then if he prays, all the knots are undone. Thus, he wakes up in the morning energetic and in a good mood; otherwise, he wakes up in a bad mood and lazy.”These are the words of the narration of Janab al-Dawraqi.

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "Indeed, when a servant sleeps, Satan ties three knots upon him. Then, if he wakes up during the night and remembers Allah, one knot is untied; if he performs ablution, two knots are untied; then if he performs two units of prayer, all the knots are untied. Therefore, untie the knots of Satan, even if it is with just two units of prayer."

Just as he (Satan) ties knots on the nape of men, a woman can also untie the knots of Satan from herself, like a man, by remembering Allah, performing ablution, and offering prayer.

Abu Sufyan reports that I heard Jabir (may Allah be pleased with him) say that the Messenger of Allah (peace and blessings be upon him) said: "Knots are tied with a rope on the head of every man and woman when they sleep. Then if he wakes up and remembers Allah, one knot is untied. Then when he gets up, performs ablution, and prays, all the knots are untied." Abu Sufyan narrates from Jabir (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Every man and woman, when they sleep at night, a knot is tied on them with a rope." He narrated the hadith similar to the one above and added: "And in the morning he is light-hearted and cheerful, and he has attained much goodness." Imam Abu Bakr (may Allah have mercy on him) says that 'al-jareer' means rope.