The following is a description of the book about historic event of Ghadir
Khumm.
The Farewell Pilgrimage
Ten years after the migration (hijrah), the Messenger of Allah
[peace and blessings be upon him and his Progeny] ordered to his close
followers to call all the people in different places to join him in his
last pilgrimage. On this pilgrimage he taught them how to perform the pilgrimage
in a correct and unified form.
This was first time that the Muslims with this magnitude gathered in one place in the presence of their leader, the Messenger of Allah [s]. On his way to Makkah, more than seventy thousand people followed Prophet [s]. On the fourth day of Dhu'l-Hijjah more than one hundred thousand Muslims had entered Makkah.