The saying of Allah the Exalted: "And it is an announcement from Allah and His Messenger to the people on the day of the greater Hajj"

Sayyiduna Samurah (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "The day of the Greater Hajj is the day on which Abu Bakr led the people in Hajj."
Imam al-Tabarani recorded it, and its narrators are the narrators of the Sahih, except for Mu'adh bin Hisham; he says: "I found this in my father's writing."

Sayyiduna Samurah bin Jundub (may Allah be pleased with him) narrates: At the time of the Conquest, the Prophet (peace and blessings be upon him) said: "This is the year of the Greater Hajj." The Prophet (peace and blessings be upon him) said: "The Hajj of the Muslims and the Hajj of the idolaters coincided over three consecutive days, and the Hajj of the Christians and the Jews coincided over three consecutive days. So in a single year the Hajj of the Muslims, the idolaters, the Christians and the Jews coincided over six consecutive days. Since the heavens and the earth were created, it never coincided like this before this year, and after this year it will never coincide until the Hour is established."
Imam al-Tabarani recorded it, and its narrators have been declared trustworthy; however, its text is munkar (denounced).

Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates: The Arabs used to declare one month lawful in one year and two months lawful in another year, so they would reach the correct time of Hajj only once every twenty-six years. This is the postponement (nasi') that Allah Almighty mentioned in His Book. When the year came in which Sayyiduna Abu Bakr (may Allah be pleased with him) led the people in Hajj, that year coincided with the true Hajj, so Allah Almighty named it the Greater Hajj. Then in the following year the Prophet (peace and blessings be upon him) performed Hajj, and the people began to keep correct count of the new moons. The Prophet (peace and blessings be upon him) said: "Indeed, time has come round to the way it was on the day Allah Almighty created the heavens and the earth."
Imam al-Tabarani recorded it in al-Mu'jam al-Awsat, and its narrators are thiqat (trustworthy).

Sayyiduna Ali (may Allah be pleased with him) narrates: When ten verses of Surah al-Tawbah were revealed to the Prophet (peace and blessings be upon him), the Prophet (peace and blessings be upon him) called Sayyiduna Abu Bakr (may Allah be pleased with him) and sent him with them so that he would recite them to the people of Makkah. Then the Prophet (peace and blessings be upon him) called me and said to me: "Go after Abu Bakr; wherever you meet him, take the document from him, and you recite these verses to the people of Makkah." I caught up with Sayyiduna Abu Bakr (may Allah be pleased with him) and took the document from him. Sayyiduna Abu Bakr (may Allah be pleased with him) returned to the Prophet (peace and blessings be upon him) and said: "O Messenger of Allah! Has something been revealed concerning me?" The Prophet (peace and blessings be upon him) said: "No, but Sayyiduna Jibril (peace be upon him) came to me and said: 'No one will discharge this duty on your behalf except you yourself or a man from your family.'"
Abdullah bin Ahmad recorded it. Its chain contains a narrator, Muhammad bin Jabir al-Suhaymi, who is da'if (weak), though he has also been declared trustworthy.