Ahl u Sunnah claim that Abu Bakr bin Quhafa was first to accept Islam (even before Imam Ali Ibn Abi Talib (as) aboit whom there are numerous authentic narrations proving his earliest Islam) while the fact is that there is not a single authentic narration in whole Sunni corpus which supports their claim.
Here is a narration often quoted to prove his earliest Islam but it is not free from defect.
Ahmad bin U'mro bin Abi Asim (Died 287 AH) narrates :
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، ثنا عُقْبَةُ بْنُ خَالِدٍ، عَنْ شُعْبَةَ، عَنْ سَعِيدٍ الْجُرَيْرِيِّ عَنْ أَبِي نَضْرَةَ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ قَالَ: لَمَّا رَأَى أَبُو بَكْرٍ تَثَاقُلَ النَّاسِ عَنْ بَيْعَتِهِ قَالَ: أَلَسْتُ صَاحِبَ كَذَا أَلَسْتُ صَاحِبَ كَذَا أَلَسْتُ أَوَّلَ مَنْ أَسْلَمَ أَلَسْتُ أَوْلَى النَّاسِ بِهَا؟
Abu Nadrah narrates from Abu Saeed Al-Khudri who said : When Abu Bakr saw that people were reluctant in accepting his pledge of allegiance, He said : Am I not a following person ? Am I not the person who accepted Islam at first, Am I not a person who desreves this (Caliphate) more then others.
Investigator of this book Nasir Al-A'jmi in footnotes has said following :
ورجع الترمذي وابن ابي حاتم انقطاع هذه الرواية، وذالك لأن ابا نضرة لم يسمع من ابي بكر الصديق.
Tirmidhi and Ibn Abi Hatim have pointed towards disconnection in this narration, This is because Abu Nadra hasn't heard from Abu Bakr 'Siddiq'.
Tirmidhi (Died 279 AH) has mentioned its problem in his book of ilal. He said :
قَالَ أَبُو عِيسَى الصَّحِيحُ عَنْ أَبِي نَضْرَةَ قَالَ: قَالَ أَبُو بَكْرٍ هَكَذَا رَوَى أَصْحَابُ شُعْبَةَ لَا يَذْكُرُونَ فِيهِ عَنْ أَبِي سَعِيدٍ
Abu Essa (Tirmidhi) said : Correct version is Abu Nadhra narrated that Abu Bakr said this. Companions of Sh'uba havw not mentioned in its chain Abu Saeed (Al-Khudri).
Kitab Al-ilal Al-Kabeer - Tirmidhi // Page 231 // Edn. Dar ul Kutub Al-Ilmiyyah Beriut Lebanon.
This quote of Tirmidhi can be found in Sunan Tirmudhi also.
Hence it is proven that this narration is a Disconnected (Weak) narration and addition of Abu Saeed Al-Khudri in its chaib is a mistake from some narrators.
