From such hadiths where the word "Shi'a" was proclaimed by the grand Prophet (ص), it can be understood that the first person who sowed the seeds of Shiism in the land of Islam was the Messenger of Allah (ص)

Dailami, Ferdaus al-Akhbar, V.3, page 88; Qunduzi, Yanabi al-Muwadda, V.2, page 245; Baladhuri, Ansab al-Ashraf, V.2, page 182; Ibn Asaker, Tarikh Madinah-Damishq, V.42, page 333.

Jaber ibn Abdullah narrates that “We were sitting in the company of the holy Prophet (s.a.w.a.) when Ali approached us from the front. When the Prophet's eye fell on him, he said, "I swear by the One who holds my life in His power, he and his Shi’ites (followers) will be the victors and champions on the Day of Resurrection." And the verse 7 of Sura Al-Baiyyineh was revealed: "As for those who believed and did righteous deeds, they are the best of creatures." Haythami, Maj’mah al-Zawaid, V. 9, page 131.

Also, Ganji narrated with reference from Abu Saeed al-Khudri that the Prophet (s.a.w.a.) looked at Ali and said, "He and his followers are the triumph ones of the Day of Resurrection." He goes on to say: "I heard this hadith from numerous groups and via different ways. Ganji Shafei, Kifayatu’t-Talib, page 313-314.

And Munawi narrates this hadith as: “Ali’s followers are the victorious ones”. Munawi, Kunuz al-Haqaiq, V.1, page 2515, V.17