Narrated Ibn 'Abbas:

"The Messenger of Allah (s.a.w.a.) dispatched Abu Bakr ordering him to announce these statements. Then 'Ali followed him. When Abu Bakr was at a particular road, he heard the heavy breathing of Al-Qiswa, the she camel of the Messenger of Allah (s.a.w.a.), so Abu Bakr appeared frightened because he thought that it was the Messenger of Allah (s.a.w.a.). When he saw that it was 'Ali, he gave him the letter of the Messenger of Allah (s.a.w.a.), and told 'Ali to announce the statements. So he left to perform Hajj. During the day of At-Tashriq 'Ali stood to announce: 'The protection of Allah and His Messenger is removed from every idolater. So travel in the land for four months. There is to be no idolater performing Hajj after this year, nor may anyone perform Tawaf around the House while naked. None shall enter Paradise but a believer.'