Leader of Hajj
It is recorded with regards to Hazrat Abu Bakr (ra) being the leader for Hajj, that in 9 AH, the Holy Prophet (sa) appointed him as the Amir [leader] of Hajj and sent him to Mecca. Details of this are that when the Holy Prophet (sa) returned from Tabuk, he decided to perform Hajj. He was told that the disbelievers join in with others on the occasion of Hajj, and so they would be present there reciting idolatrous incantations while circling the Kabah without any clothes on. Upon hearing this, the Holy Prophet (sa) decided not to perform Hajj that year, and appointed Hazrat Abu Bakr (ra) as the leader.
(Ibn Hisham, Al-Raud al-Unf fi Tafsir al-Sirah al-Nabawiyyah, Vol. 4, Hajj Abi Bakr (ra) bi al-Nas… [Beirut, Lebanon: Dar al-Kutub al-‘Ilmiyyah], pp. 318-219), (Badr al-Din Mahmud Ibn Ahmad Aini, ‘Umdat al-Qari, Kitab al-Hajj, Bab la Yatufu bi al-Bait ‘Uryan, Vol. 9 [Beirut, Lebanon: Dar Ihya’ al-Turath al-‘Arabi, 2003], p. 384)
Hazrat Abu Bakr (ra) set out from Madinah along with 300 companions, and the Holy Prophet (sa) sent 20 animals for sacrifice along with them. The Holy Prophet (sa) put collars around their necks and marked them himself in order to indicate that these were sacrificial animals. Hazrat Abu Bakr (ra) also took five sacrificial animals of his own.
(‘Ali bin Burhan al-Din al-Halabi, Al-Sirah al-Halabiyyah, Vol. 3, Bab Sarayuh wa Bu’uthuh… [Beirut, Lebanon: Dar al-Kutub al-‘Ilmiyyah, 2002], p. 295)