- Ali’s generosity: Ali (AS) would do manual labor while fasting and provide his wages to the needy. He would give his own Iftaar (food used to break one’s fast) away to the hungry and remain hungry himself. His generosity was to such an extent that God praised his sacrifice within the Holy Quran .
- The Ark that saves: The Prophet described Ali and also the 11 guides from Ali’s progeny as being the rescue ship of people, kind of like Noah’s Ark. Whoever clings to them will be saved, and whoever infringes on them will drown.
- The Straight Path: During their daily prayers, Muslims ask God to guide them to the “Straight Path” . The Prophet explained to the people that the Divine Straight Path that they ask from God on a daily basis is Ali and his successors.
- Ali’s knowledge: The Prophet reminded the people on several occasions that, “I am the town of Knowledge and Ali is its gate; whoever decides to seek out the town of Knowledge must enter from its gate”.
- The Teacher of the Quran: The Prophet explicitly told the people that whoever wishes to understand the Holy Quran and gain guidance from it after him must refer to his successor, meaning Ali ibn Abi Talib (AS). He said “Ali is my successor upon my nation and [my successor] upon the interpretation of the book of God Almighty. He is the commander of the Quran who will guide the people through the Quran. If a portion of the Quran is not clear for someone and that they did not learn it from me, they must refer to him for he, like I, possesses the whole knowledge of the Quran. Ali is with the Quran and also the Quran is with Ali, and these two will not separate from one another until they arrive at me in the Pool of Kawthar.”
– The Prophet’s Nafs: The Prophet left no room for doubt for his friends and enemies that Ali was the apple of his eye, his trusted confident, his heir, and successor. Most importantly, as confirmed by the Holy Quran, Ali ibn Abi Talib (AS) reached the rank of the Prophet’s Nafs (self) in the event of Mubahila.
The characteristics that made Imam Ali unique are far more than the cases cited. There are many other distinguished characteristics of him which both his friends and enemies has testified to. They can be found in the references of these 3 articles.
Taken from “Hidden from the Eyes of the World: Who Are the Shia and What Do They Say?” by Masoud Basiti & Zahra Moradi
 وَ يُطْعِمُونَ الطَّعَامَ عَلىَ حُبِّهِ مِسْكِينًا وَ يَتِيمًا وَ أَسِيرًا * إِنَّما نُطْعِمُكُمْ لِوَجْهِ اللَّهِ لَا نُرِيدُ مِنكُمْ جَزَاءً وَ لَا شُكُوراً
The Holy Quran, Surah al-Insan (76:8,9)
 Bihar al-Anwar, Volume 23, Page 105
 اِهْدِنَا الصِّراطَ الْمُسْتَقِيم
The Holy Quran, Surah Al-Fatihah (1:6)
 Bihar al-Anwar, Volume 37, Page 212.
 al-Mustadrak alaa al-Sahihain (by Hakim Neyshabouri), Volume 3, Page 136
 Mustadrak alaa al-Sahihain (by Hakim Neyshabouri), Volume 3, Page 34
 The Holy Quran, Surah Āl ʻImrān (3:61)