In one narration the wording is: "Whoever recites 'Subhanallah' (Glory be to Allah), twenty good deeds are recorded for him and twenty of his sins are erased." That is, in the wording of this narration the narrator has no doubt.
Ahmad and Bazzar recorded it, except that he recorded these words: "Whoever recites 'Subhanallah', twenty good deeds are recorded for him and twenty of his sins are erased; whoever recites 'Al-hamdu lillah' (All praise is for Allah) receives a reward like that; whoever recites 'La ilaha illallah' (There is no deity except Allah) receives a reward like that; and whoever recites 'Allahu akbar' (Allah is the Greatest) of his own accord, thirty good deeds are recorded for him and thirty of his sins are erased." The narrators of both narrations are the narrators of the Sahih.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأذكار / 16838
Hadith Gradingمحدثین:إسنادہ صحیح
Hadith Takhrij«اخرجه البزار فى المسند (3074) اخرجه احمد فى المسند (8079)»