Sunan Ibn Majah Book 0, Hadith 150

حَدَّثَنَا أَحْمَدُ بْنُ سَعِيدٍ الدَّارِمِيُّ، حَدَّثَنَا يَحْيَى بْنُ أَبِي بُكَيْرٍ، حَدَّثَنَا زَائِدَةُ بْنُ قُدَامَةَ، عَنْ عَاصِمِ بْنِ أَبِي النَّجُودِ، عَنْ زِرِّ بْنِ حُبَيْشٍ، عَنْ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ، قَالَ كَانَ أَوَّلَ مَنْ أَظْهَرَ إِسْلاَمَهُ سَبْعَةٌ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ وَأَبُو بَكْرٍ وَعَمَّارٌ وَأُمُّهُ سُمَيَّةُ وَصُهَيْبٌ وَبِلاَلٌ وَالْمِقْدَادُ فَأَمَّا رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ فَمَنَعَهُ اللَّهُ بِعَمِّهِ أَبِي طَالِبٍ وَأَمَّا أَبُو بَكْرٍ فَمَنَعَهُ اللَّهُ بِقَوْمِهِ وَأَمَّا سَائِرُهُمْ فَأَخَذَهُمُ الْمُشْرِكُونَ وَأَلْبَسُوهُمْ أَدْرَاعَ الْحَدِيدِ وَصَهَرُوهُمْ فِي الشَّمْسِ فَمَا مِنْهُمْ مِنْ أَحَدٍ إِلاَّ وَقَدْ وَاتَاهُمْ عَلَى مَا أَرَادُوا إِلاَّ بِلاَلاً فَإِنَّهُ قَدْ هَانَتْ عَلَيْهِ نَفْسُهُ فِي اللَّهِ وَهَانَ عَلَى قَوْمِهِ فَأَخَذُوهُ فَأَعْطَوْهُ الْوِلْدَانَ فَجَعَلُوا يَطُوفُونَ بِهِ فِي شِعَابِ مَكَّةَ وَهُوَ يَقُولُ أَحَدٌ أَحَدٌ ‏.‏

It was narrated that 'Abdullah bin Mas'ud said:"The first people to declare their Islam publicly were seven: The Messenger of Allah, Abu Bakr, 'Ammar and his mother Sumayyah, Suhaib, Bilal and Miqdad. With regard to the Messenger of Allah, Allah protected him through his paternal uncle Abu Talib. With regard to Abu Bakr, Allah protected him through his people. As for the rest, the idolators seized them and made them wear coats of chain-mail and exposed them to the intense heat of the sun. There was none of them who did not do what they wanted them to do, except for Bilal. He did not care what happened to him for the sake of Allah, and his people did not care what happened to him. Then they gave him to the children who took him around in the streets of Makkah while he was saying, 'Ahad, Ahad (One, One)