You must read al-T'ibun al'Abidun

569. Muhammad Bin Yahya, from Ahmad Bin Muhammad, from Ali Bin Al-Hakam, from Ali Bin Abu Hamza, from Abu Baseer, who has said: Abu Ja’far عليه الصلاة والسلام said: ‘Are you عليه الصلاة والسلام reciting: “[9:112] They who repent (Al-Ta’iboun), who serve (Al-Abidoun)”?’ So he عليه الصلاة والسلام said: ‘No. Recite “Al-Ta’ibeen Al-Abideen” upto the end of it’. So I asked about the reason for that, he عليه الصلاة والسلام said: ‘He عز وجل Bought from the Believers (their own selves), the repentant (and) the worshippers’.