The Event at Ghadir Khumm (18 Dhu’l-Hijja, 10 AH)
Returning from the Farewell Pilgrimage, at the place called Ghadir Khumm (a watering hole between Mecca and Medina), the Prophet gathered the Muslims who were traveling with him and delivered a speech. Zayd ibn Arqam was among those present.
The specific declaration: “Man kuntu mawlahu fa-‘Ali mawlahu” — “Whoever’s mawla I am, Ali is their mawla.” Some accounts extend this to the full formula: “O God, befriend whoever befriends him, and be an enemy to whoever is an enemy to him.”
Zayd ibn Arqam narrated this in multiple chains preserved in Tirmidhi, Nasa’i, Ibn Majah, and the musnad collections. His narration is among the most frequently cited and strongest in hadith criticism.
The Hadith of the Two Weighty Things
Zayd also narrated the Hadith al-Thaqalayn (Hadith of the Two Weighty Things): “I am leaving among you two weighty things — the Book of God and my household (Ahl al-Bayt). If you hold to them both, you will not go astray.”
In the Ismaili tradition, these two hadiths together establish the axis of religious authority: the Quran (zahir) and the living Imam from the Ahl al-Bayt (batin — the one who holds its inner meaning).
His Final Years
Zayd retired to Kufa, where he lost his sight in old age. During the lead-up to Karbala (60-61 AH), he was among the elderly Companions in Kufa who wept over the impossible position of Husayn ibn Ali — aware of what was coming, unable to prevent it.
See also: Imamah, Understanding Walayah, Seerah Al Zubayr Ibn Al Awwam, Seerah Sad Ibn Muadh, Ismaili Nass