Imam Ali (a.s.) is the benchmark for recognizing the truth
The character of the Commander of the Faithful (a.s.) was exceptional from birth to martyrdom. He was born inside the Ka’bah – which was unparalleled before his birth and remained unparalleled thereafter. And he was martyred while he was praying in the mosque. The Commander of the Faithful (a.s.) spent all the time between these two points in jihad, patience for the sake of God, acquiring knowledge and insight, and moving on the path of divine satisfaction. Early in his childhood, the hand of divine acumen gave Ali ibn Abi Talib (a.s.) to the Holy Prophet (s.w.a.). The Commander of the Faithful (a.s.) was only six years old when the Holy Prophet (s.w.a.) brought him to his own house from the house of Abi Talib. The Commander of the Faithful (a.s.) was educated by the Holy Prophet (s.w.a.)… since his childhood. He announced his faith in the Holy Prophet (s.w.a.) when he was a child. He prayed with the Holy Prophet (s.w.a.). He engaged in jihad alongside the Holy Prophet (s.w.a.). He made sacrifices for the Holy Prophet (s.w.a.). During his lifetime, he tried his utmost to administer justice, promote the religion of God and protect Islam before and after the Holy Prophet (s.w.a.) passed away. From the Holy Prophet’s (s.w.a.) perspective, the Commander of the Faithful (a.s.) is the criterion for truth and justice. Shia and Sunni Muslims have quoted the Holy Prophet as saying, “Ali is with truth, and truth is with Ali. Truth revolves around him wherever he is.” This was how the lifestyle of the Commander of the Faithful (a.s.) was.
Imam Ali’s (a.s.) features as narrated by prophet Muhammad (pbuh)
Knowledge is one of the criteria. Regarding his knowledge, both Shia and Sunni narrations confirm that the Holy Prophet said, “I am the city of knowledge, and Ali is the gate to it.” This is the best testimony to Imam Ali’s knowledge. Regarding his jihad, Allah the Exalted said, “And there is the type of man who gives his life to earn the pleasure of Allah.” [The Holy Quran, 2: 207] This Quranic verse describes the selflessness of the Commander of the Faithful. There are no other such revelations about other people in the Quran. Regarding his charitable activities, there is the ayah, “And they feed, for the love of Allah, the indigent, the orphan, and the captive.” [The Holy Quran, 76: 8] This ayah is about the Commander of the Faithful and his family. “Your (real) friends are (no less than) Allah, His Messenger, and the (fellowship of) believers – those who establish regular prayers and regular charity, and they bow down humbly (in worship).” [The Holy Quran, 5: 55] Everyone says that this ayah is about Imam Ali (a.s.). He had each and every one of the qualifications specified in Islam – including knowledge, piety, charitable activities, selfless efforts, and jihad. Who would deny the fact that Imam Ali (a.s.) had these qualifications?