بِسْمِ اللَّـهِ الرَّحْمَـٰنِ الرَّحِيم
The Arabic word Shi'ah means "follower."
The Holy Qur'an reads, "One of his (Noah's) followers (Shi'ah) is Ibrahim." (37:83)
In the Islamic terminology Shiism refers to a sect believing that the holy Prophet (a.s), before his death and on many other occasions, including Dhu'l-Hijjah 18th, the twentieth year of Hijrah – known as the Day of Ghadir – and in the presence of a large gathering, appointed 'Ali (a.s) as his successor, that is as the caliph of the Muslims and the political, scientific and religious authority after him.
A word of explanation is warranted here. Concerning the Caliphate issue, the Immigrants (Muhajirun) and the Helpers (Ansar) divided into two groups after the death of the holy Prophet: one group believed that the holy Prophet had not neglected the issue of the leadership of the Islamic community and had appointed his successor, 'Ali Ibn Abi-Talib, the first person who declared his conviction in the Prophethood of Muhammad.
This group consisted of some Immigrants and Helpers, headed by the noblemen of the Bani-Hashim clan, as well as by some of the great companions of the Prophet, such as Salman, Abu-Dharr, al-Miqdad, Khabbab ibn al-Aratt and others; they were called "the Shiites" of 'Ali, the Commander of the Faithful.
In fact, it was the holy Prophet himself who entitled 'Ali's followers as such. When appointing 'Ali ibn Abi-Talib, he said, "By the one in whose hands lies my life, he ('Ali) and his followers are saved on the Day of Resurrection
So, the Shiites are the Muslims who were organized into a group in the early days of Islam because they believed that the rank of Wilayah, the leadership of the Islamic community, was divinely ordained. This sect is still faithful to following the Prophet and his family.
The position of the Shiites is thus clear, contrary to the claims of some ignorant or malicious people who maintain that Shiism was a later development, not existing in the early period of Islam.
For further information, see the following books: Asl al-Shi'ah wa Usuluha, al-Muraja'at, and A'yan al-Shi'ah.
The other group maintains that Caliphate was an elective institution. So they swore allegiance to Abu-Bakr, and were later called the Sunnis.
Thus, against many principles in common, the two sects were divided due to their differing views on the issue of the Prophet's successorship. Both sects were originally formed by some Immigrants (Muhajirun) and Helpers (Ansar).
 Jalal al-Din al-Suyuti,
in his al-Durr al-Manthur, vol. 6,
narrates this tradition while commenting on the Qur'anic verse:
"(And) lo! Those who believe and do good deeds are the best of the created beings." (98:6).
رَبَّنَا تَقَبَّلْ مِنَّا إِنَّكَ أَنتَ السَّمِيعُ الْعَلِيمُ
اَللَّهُمَّ صَلِّ عَلى مُحَمَّدٍ وَّآلِ مُحَمَّدٍ وَّعَجِّلْ فَرَجَهُمْ
وَالْعَنْ أَعْدَائَهُمْ اَجْمَعِيْن
🤲 اللھم عجل لولیک الفرج(ع)🤲
فی امان لله