this hadeeth is from al-kafi, and it is with sahih shia chain inshallah

this hadeeth also proves that the verse of completion of deen was revealed in ghadeer

in arabic version, it is in al-kafi, vol 1, page 289, hadeeth 4

here is the english translation for you

H 760, Ch. 64, h 4

Ali ibn Ibrahim from his father from Ibn Abu ‘Umayr from ‘Umar ibn Udhaynah from Zurarah and Fudayl ibn Yasar and Bukayr ibn A’yan and Muhammad ibn Muslim and Burayd ibn Muiawiyah and Abu ‘1- Jarud, together, that Abu Ja’far (p.b.u.h.) said:

“Allah, to Whom belong Might and Majesty, charged His Messenger with the Mastership of Ali, and sent down to him: Your Master is only Alldh, and His Messenger and those who believe who perform the prayer and pay zakat. He decreed the Mastership of those in authority, although they (the people) did not understand what it was. Allah command Muhammad (p.b.u.h.a.h.p.) to interpret (and explain) Mastership for them as he had interpreted (and explained) prayer, zakat, fasting and hajj. When this came to him from Allah, the mind of the Messenger of Allah (p.b.u.h.ah.p.) became straitened by it and he became afraid lest they (the people) abandon their religion and come to deny it. So his mind was staitened and he consulted with his Lord, to Whom belong Might and Majesty; and Allah to Whom belong Might and Majesty revealed to him: O Messenger, deliver that which has been sent down to thee from thy Lord; for if thou cost not, thou wig not have delivered His Message. Allah will protect thee from men (al-Ma’idah, 5:67). He complied with the command of Allah, may remembrance of Him be exlated, and endorsed the Mastership of Ali on the day of Ghadir Khumm. He convened the communal prayer, and he commanded the people that those who were witnesses should inform those who were absent.”—’Umar ibn Udhaynah said: `Ali but Abu’l-Jarudsaid: ‘Abu Ja’far (p.b.uh.) said: “One divine precept came down after another, and the Mastership was the last divine ordinance. And Allah, to Whom belong Might and Majesty, sent down: Today I have completed your religion for you, and I have perfected My blessing upon you ( al-Matidah, 5 :3 ).” Abu Ja’ far (p.b.uh. ) said: “Allah, to Whom belong Might and Majesty, said: ‘I shall not send down (any ordinance) to you after this ordinance: I have completed the divine ordinances for you.’ ” ‘ “

the narrators of this chain are very famous,

ali bin ibrahim is thiqa

his father is also thiqa as has been explained by allama khoi in his maujam, vol 1,page 316, narrator 332

mohammad bin abi umair is one of the ashaab-ul-ijmaa, he is thiqa for sure

umar bin aznia is thiqa as well [maujam vol 13, page 18-19, narrator 8699

and he is quoting from some really great narrators like zurarah, fadel bin yasar

so the chain is inshallah sahih