What were the two wives of the Prophet Muhammad (peace be upon him) to whom Allah said "If you two return in repentance" (66.4)?
 Narrated `Abdullah bin `Abbas:                     I had been eager to ask `Umar about the two ladies from among the wives of the Prophet regarding whom Allah said (in the Qur'an saying): If you two (wives of the Prophet namely Aisha and Hafsa) turn in repentance to Allah your hearts are indeed so inclined (to oppose what the Prophet likes) (66.4), till performed the Hajj along with `Umar (and on our way back from Hajj) he went aside (to answer the call of nature) and I also went aside along with him carrying a tumbler of water. When he had answered the call of nature and returned. I poured water on his hands from the tumbler and he performed ablution. I said, "O Chief of the believers! ' Who were the two ladies from among the wives of the Prophet to whom Allah said: 'If you two return in repentance (66.4)? He said, "I am astonished at your question, O Ibn `Abbas. They were Aisha and Hafsa." Then `Umar went on relating the narration and said. "I and an Ansari neighbor of mine from Bani Umaiya bin Zaid who used to live in `Awali Al-Medina, used to visit the Prophet in turns. He used to go one day, and I another day. When I went I would bring him the news of what had happened that day regarding the instructions and orders and when he went, he used to do the same for me. We, the people of Quraish, used to have authority over women, but when we came to live with the Ansar, we noticed that the Ansari women had the upper hand over their men, so our women started acquiring the habits of the Ansari women. Once I shouted at my wife and she paid me back in my coin and I disliked that she should answer me back. She said, 'Why do you take it ill that I retort upon you? By Allah, the wives of the Prophet retort upon him, and some of them may not speak with him for the whole day till night.' What she said scared me and I said to her, 'Whoever amongst them does so, will be a great loser.' Then I dressed myself and went to Hafsa and asked her, 'Does any of you keep Allah's Apostle angry all the day long till night?' She replied in the affirmative. I said, 'She is a ruined losing person (and will never have success)! Doesn't she fear that Allah may get angry for the anger of Allah's Apostle and thus she will be ruined? Don't ask Allah's Apostle too many things, and don't retort upon him in any case, and don't desert him. Demand from me whatever you like, and don't be tempted to imitate your neighbor (i.e. `Aisha) in her behavior towards the Prophet), for she (i.e. Aisha) is more beautiful than you, and more beloved to Allah's Apostle. In those days it was rumored that Ghassan, (a tribe living in Sham) was getting prepared their horses to invade us. My companion went (to the Prophet on the day of his turn, went and returned to us at night and knocked at my door violently, asking whether I was sleeping. I was scared (by the hard knocking) and came out to him. He said that a great thing had happened. I asked him: What is it? Have Ghassan come? He replied that it was worse and more serious than that, and added that Allah's Apostle had divorced all his wives. I said, Hafsa is a ruined loser! I expected that would happen some day.' So I dressed myself and offered the Fajr prayer with the Prophet. Then the Prophet entered an upper room and stayed there alone. I went to Hafsa and found her weeping. I asked her, 'Why are you weeping? Didn't I warn you? Have Allah's Apostle divorced you all?' She replied, 'I don't know. He is there in the upper room.' I then went out and came to the pulpit and found a group of people around it and some of them were weeping. Then I sat with them for some time, but could not endure the situation. So I went to the upper room where the Prophet was and requested to a black slave of his: "Will you get the permission of (Allah's Apostle) for `Umar (to enter)? The slave went in, talked to the Prophet about it and came out saying, 'I mentioned you to him but he did not reply.' So, I went and sat with the people who were sitting by the pulpit, but I could not bear the situation, so I went to the slave again and said: "Will you get he permission for `Umar? He went in and brought the same reply as before. When I was leaving, behold, the slave called me saying, "Allah's Apostle has granted you permission." So, I entered upon the Prophet and saw him lying on a mat without wedding on it, and the mat had left its mark on the body of the Prophet, and he was leaning on a leather pillow stuffed with palm fires. I greeted him and while still standing, I said: "Have you divorced your wives?' He raised his eyes to me and replied in the negative. And then while still standing, I said chatting: "Will you heed what I say, 'O Allah's Apostle! We, the people of Quraish used to have the upper hand over our women (wives), and when we came to the people whose women had the upper hand over them..." `Umar told the whole story (about his wife). "On that the Prophet smiled." `Umar further said, "I then said, 'I went to Hafsa and said to her: Do not be tempted to imitate your companion (`Aisha) for she is more beautiful than you and more beloved to the Prophet.' The Prophet smiled again. When I saw him smiling, I sat down and cast a glance at the room, and by Allah, I couldn't see anything of importance but three hides. I said (to Allah's Apostle) "Invoke Allah to make your followers prosperous for the Persians and the Byzantines have been made prosperous and given worldly luxuries, though they do not worship Allah?' The Prophet was leaning then (and on hearing my speech he sat straight) and said, 'O Ibn Al-Khattab! Do you have any doubt (that the Hereafter is better than this world)? These people have been given rewards of their good deeds in this world only.' I asked the Prophet . 'Please ask Allah's forgiveness for me. The Prophet did not go to his wives because of the secret which Hafsa had disclosed to `Aisha, and he said that he would not go to his wives for one month as he was angry with them when Allah admonished him (for his oath that he would not approach Maria). When twenty-nine days had passed, the Prophet went to Aisha first of all. She said to him, 'You took an oath that you would not come to us for one month, and today only twenty-nine days have passed, as I have been counting them day by day.' The Prophet said, 'The month is also of twenty-nine days.' That month consisted of twenty-nine days. `Aisha said, 'When the Divine revelation of Choice was revealed, the Prophet started with me, saying to me, 'I am telling you something, but you need not hurry to give the reply till you can consult your parents." `Aisha knew that her parents would not advise her to part with the Prophet . The Prophet said that Allah had said: 'O Prophet! Say To your wives; If you desire The life of this world And its glitter, ... then come! I will make a provision for you and set you free In a handsome manner. But if you seek Allah And His Apostle, and The Home of the Hereafter, then Verily, Allah has prepared For the good-doers amongst you A great reward.' (33.28) `Aisha said, 'Am I to consult my parents about this? I indeed prefer Allah, His Apostle, and the Home of the Hereafter.' After that the Prophet gave the choice to his other wives and they also gave the same reply as `Aisha did."