It was narrated that 'Abbad bin 'Abdullah said:
"'Ali said: 'I am the slave of Allah and the brother of His Messenger. I am the greatest teller of the truth (Siddiq Akbar), and no one will say this after me except a liar. I prayed seven years before the people." (FR)
English reference (FR): Vol. 1, Book 1, Hadith 120 (FR)
Arabic reference (FR): Book 1, Hadith 125 (FR)