Abu Bakr al-Siddiq sent him during the pilgrimage which the Prophet ﷺ had placed him in charge of, the year before the Farewell Pilgrimage, on the Day of Sacrifice, along with a small group to announce to the people, "After this year, no polytheist may perform the pilgrimage, and no one may circumambulate the House while naked."
أن أبا بكر الصديق بعثه في الحجة التي أمره النبي ﷺ قبل حجة الوداع يوم النحر في رهط يؤذن في الناس: لا يحج بعد العام مشرك، ولا يطوف بالبيت عريان.
Bukhari narrated it in Maghazi (4363) and Muslim in Hajj (1347), both from the hadith of Ibn Shihab Zuhri, from Humayd bin Abdul-Rahman, from Abu Hurairah, and he mentioned it. In a version reported by Bukhari (369), Abu Hurairah said, "Abu Bakr sent me during that Hajj among the callers on the Day of Sacrifice to proclaim at Mina that no polytheist shall perform Hajj after this year, and no one shall perform tawaf around the House naked."Humayd bin Abdul-Rahman said, "Then the Messenger of Allah ﷺ sent Ali after him and ordered him to proclaim 'Baraah'." Abu Hurairah said, "So Ali proclaimed with us among the people of Mina on the Day of Sacrifice, no polytheist shall perform Hajj after this year, and no one shall perform tawaf around the House naked."Ibn Ishaq said, Hakeem bin Hakeem bin Abbad bin Hunayf narrated to me, from Abu Jafar Muhammad bin Ali, that he said, "When Baraah was revealed to the Messenger of Allah ﷺ, he had already sent Abu Bakr Siddiq to lead the people in Hajj. It was said to him, 'O Messenger of Allah, why not send it to Abu Bakr?' He said, 'No one shall deliver it on my behalf except a man from my own household.'" He then mentioned something similar, except that this version is mursal.It has also been narrated with a connected chain. Tirmidhi (3090), Ahmad (13214), and Juzjani in al-Abatil (128) all narrated it from the hadith of Hammad bin Salama, from Simak, from Anas bin Malik, that the Messenger of Allah ﷺ sent Baraah with Abu Bakr Siddiq, and when he reached Dhul-Hulayfa, he said, "No one shall deliver it except me or a man from my own household."Ibn Adi mentioned this hadith in the biographical entry on this Simak and said, "I do not know of anyone who narrates it from Simak other than Hammad." This Simak is Ibn Harb bin Aws, who suffered a change in his memory toward the end of his life, so he would sometimes be prompted with material and repeat it, and he is not considered particularly strong. For this reason, this text was deemed objectionable in his narration, objected to by Khattabi, Juzjani, Ibn Taymiya, Ibn Qayyim, and others.It has also been narrated through other chains from Ibn Abbas and others, but none of them is free from defect. I have discussed this hadith in detail in the book on Hajj, in the chapter on the obligation of covering one's private parts during tawaf.