Quran says: (5:55-56)

“Only Allah is your Wali (Guardian-master), and His Messenger, and those who believe those who keep up prayers and pay the poor-rate while they bow. And whoever takes Allah and His messenger and those who believe for a mastership, and then surely the party of Allah is they that shall be triumphant.”

About the above verses all Shia scholars state that this verse was revealed about Imam Ali. There are also many Sunni scholars who testify that this verse was revealed about Imam. There is a hadith in Musnad Ahmad bin Hunbal and Nissaie by Abu Zar Ghaffari that Imam Ali while he was praying, somebody asked help, nobody helped him, he complained that he is going empty handed from the mosque of prophet. Imam Ali stretched his hand and let him to take the ring. The holy prophet prayed about Imam Ali, and then this verse was revealed. Sunni Tafseers, thalabi, Quratbi, Tafseer Tabari and many others.

Our Sunni fellows make the meanings of Wali as friend and also say that plural wording is used in this verse after the Prophet. Shia sources say that this is verse starts from INNAMA which rule out all others and specify say about Masters, that no one is your master except these three!

Our Sunni fellows make translation that Allah is your Wali, His Prophet and those people who pray and give Zakat. We want to inform them in Arabic (waaw)  وَ  is not only used in the meanings of and, when it is used in the meanings of and it is called  وَ a'atfiya, it is also used as  وَ qasmiya, we know in Arabic society Arabs always used wallahe (by the swear of Allah),  وَ is also used as  Haliya to describe situation or position.  For example we can say JAA''a Zaid un WA HOWA Rakibun. it means Zaid came while he was riding.

Now it is easy to understand the meanings of وَهُمْ رَاكِعُونَ, it gives the meanings, they give zakat while they bowdown.

Sunni fellows make reason that plural wording is used for those people who zakat while praying. We want to tell them that Arabic language plural wording could be used for respect; there are many examples in Quran, Allah himself refer plural word for him in many verses, in Mubahala verse NISSA, ANA plural words is used while holy prophet got only Lady Fatima.

Our Sunni fellows also make different translation about the verse that those believers who pray, give zakat and bow down. Shia sources say that it is not right translation bowing down is already part of prayer. Why Allah have to say it separately that those who pray and bow down?

Sunni fellows make another excuse that if someone gives zakat in prayer, his prayer is invalid, we want to tell them that minor actions for necessary reason are allowed in prayer, but not the major actions.

Please find the proof here from Bukhari that it is allowed to make necessary minor actions while praying.Sometimes our Sunni fellows say how come Zakat is given in the form of ring or Imam Ali was not rich. Shia sources say that the word of Zakat can be used as spending something on the way of Allah as MUSTAHAB not always wajib. Our Sunni fellows try to make different reasons not to accept this verse about Imam Ali. But Shia scholars answer all those excuses one by one and prove that verse is announcing who are your masters, not friends.

Pleaase read some more details about the Hadith confirming the verse of Walayah from Shia pen.