Abu Bakr (l.a.) the liar

Abu Bakr (l.a.) and several of his close companions and his followers usually attribute the title of "Siddiq" (the most truthful) and "Siddiqul Akbar" (the most truthful of the most truthful ones).

While it is narrated in their books that:

حَدَّثَنَا مُحَمَّدُ بْنُ إِسْمَاعِيلَ الرَّازِيُّ، حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُوسَى، أَنْبَأَنَا الْعَلاَءُ بْنُ صَالِحٍ، عَنِ الْمِنْهَالِ، عَنْ عَبَّادِ بْنِ عَبْدِ اللَّهِ، قَالَ قَالَ عَلِيٌّ أَنَا عَبْدُ اللَّهِ، وَأَخُو، رَسُولِهِ ـ صلى الله عليه وسلم ـ وَأَنَا الصِّدِّيقُ الأَكْبَرُ، لاَ يَقُولُهَا بَعْدِي إِلاَّ كَذَّابٌ صَلَّيْتُ قَبْلَ النَّاسِ بِسَبْعِ سِنِينَ ‏.‏

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."
Sunan ibne Majah, Book 1 Hadith 124