Atiyyah narrates from Sayyiduna Zayd bin Arqam (may Allah be pleased with him); he said: The Messenger of Allah (peace and blessings be upon him) said: "Whoever I am the mawla of, Ali is his mawla. O Allah! Befriend whoever befriends him and be hostile to whoever is hostile to him." I asked him for more, and he said: I only go as far as I was taken.
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 5050
Atiyyah al-Awfi narrates from Sayyiduna Zayd bin Arqam (may Allah be pleased with him); he said: The Messenger of Allah (peace and blessings be upon him) came out at al-Juhfah on the day of Ghadir Khumm, holding the upper arm of Ali (may Allah be pleased with him), and said: "O people! Do you not know that I have a greater right over the believers than they have over themselves?" The Companions said: Indeed, yes, O Messenger of Allah! He said: "Then whoever I am the mawla of, this one (Ali) is his mawla."
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 5051
It is narrated from Sayyiduna Zayd bin Arqam (may Allah be pleased with him) that he heard the Messenger of Allah (peace and blessings be upon him) saying: "Whoever I am the mawla of, Ali is his mawla."
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 5052
It is narrated from Sayyiduna Zayd bin Arqam (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "How can I be at ease when the angel of the Trumpet has put the Trumpet to his mouth, waiting for when he will be commanded to blow into it?" The Companions said: Then what should we say? He said: "Say: Hasbuna Allahu wa ni'ma al-wakil (Allah is sufficient for us, and He is the best Disposer of affairs)."
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 5053