The Messenger of Allah ﷺ said, "Whoever sleeps past his witr prayer or forgets it should pray it when he wakes up or remembers it."
قال رسول الله ﷺ: من نام عن وتره، أو نسيه فليصله إذا أصبح أو ذكره.
Abu Dawud (1431) narrated it from Muhammad bin Awf, [who said], "Uthman bin Saeed narrated to us, from Abu Ghassan Muhammad bin Mutarrif Madani, from Zayd bin Aslam, from Ata bin Yasar, from Abu Saeed," and he mentioned it. Its chain is sahih.Hakim also narrated it (1/302), and from him Bayhaqi (2/480), through another route, from Uthman bin Saeed (bin Kathir bin Dinar), from Abu Ghassan, in the same way. Hakim said, "Sahih according to the criterion of the two Shaykhs." I say, this chain is the soundest of what has been narrated for this hadith.It has other daif chains, among them what Tirmidhi (465) and Ibn Majah (1188) narrated, both from the hadith of Abdul-Rahman bin Zayd bin Aslam, from his father, in the same way. Abdul-Rahman bin Zayd is daif, the people of hadith do not rely on him. Muhammad bin Yahya pointed to this. But there is no contradiction between the two hadiths, for the first hadith of Abu Saeed, "Perform Witr before you reach morning," indicates that the time of the Witr prayer ends with the rising of Fajr, so whoever deliberately fails to pray Witr before the rising of Fajr has no Witr left to pray. The second hadith indicates that whoever sleeps through his Witr, or forgets it, should pray it when he remembers, that is, as a makeup, because its time has already passed, and the preceding hadith of Ibn Umar is to be understood in this light. And even though Abdul-Rahman bin Zayd bin Aslam is weak, there is another sahih chain for it, as mentioned before.Muhammad bin Nasr said, after narrating the hadith of Abu Saeed, "What a group of our companions have held is that whoever has Fajr rise upon him without having prayed Witr should pray Witr as long as he has not prayed the morning prayer, following the reports narrated from the companions of the Prophet ﷺ that they prayed Witr after dawn. It has also been narrated from the Prophet ﷺ that he prayed Witr after morning had come. But if he has [already] prayed the morning prayer, a group of our companions said he does not make up the Witr after that, and this has also been narrated from a group of the earlier scholars. This is the view held by Shafii, Ahmad, Ishaq, and others of our companions." Kitab Witr (p. 156).He also said, "What I hold is that he prays Witr as long as he has not prayed the morning prayer. If he has [already] prayed the morning prayer, he is not obligated to make it up after that, though if he does make it up as one makes up a voluntary prayer, that is good. The Messenger of Allah ﷺ prayed the two units before Fajr after sunrise, on the night when he slept through the morning prayer until the sun rose, and he made up the two units he used to pray after Dhuhr, after Asr, on the day he was kept from them. They used to make up the night prayer, when they missed it at night, during the day, and that is good, though not obligatory." Kitab Witr (164).Abu Hanifa and his companions, and Shafii in his later view, held that it is recommended to make up the Witr prayer during the day. Tirmidhi said, following the hadith of Abu Saeed Khudri, "Some of the people of Kufa followed this hadith, and they said, a man should pray Witr when he remembers, even if it is after the sun has risen, and this is the view of Sufyan Thawri."As for what has been narrated from Ayesha, that she said, "The Messenger of Allah ﷺ would reach morning and then pray Witr," it contains Abu Nahik, concerning whose reliability there is disagreement, for Ibn Abdul-Barr considered him unknown while others deemed him reliable. It also contains a break in the chain, since his hearing from Ayesha has not been established.Imam Ahmad (26058), Tabarani in Awsat (2153), and Bayhaqi (2/479) all narrated it through the route of Ibn Jurayj, who said, "Ziyad, that is, Ibn Saad Khurasani, informed me that Abu Nahik informed him that Abu Darda used to preach to the people that there is no Witr for one who reaches morning [without praying it]. So some men among the believers went to Ayesha and told her, and she said, 'The Messenger of Allah ﷺ would reach morning and then pray Witr.'" End of report.Bayhaqi also narrated it through the hadith of Hatim bin Salim Basri, [who said], "Abdul-Warith bin Saeed narrated to us, from Khalid Haddan, from Abu Qilaba, from Umm Darda, from Abu Darda, who said, 'Sometimes I saw the Prophet ﷺ praying Witr while the people had already stood for the morning prayer.'" Bayhaqi said, "Hatim bin Salim Basri is the sole narrator of this, and he is also called Araji, and the hadith of Ibn Jurayj is sounder than this."He also narrated it, with his chain, from Ibn Umar, that the Prophet ﷺ reached morning and then prayed Witr. He said, "This is how I found it in Fawaid Kabir." Then he narrated from Abu Majliz, who said, "Ibn Umar reached morning without having prayed Witr, or he would reach morning and then pray Witr." And this is more likely. End of report. Meaning that the mawquf version is sounder.