Sayyidah Aishah Siddiqah (may Allah be pleased with her) narrates: The last instruction the Prophet (peace and blessings be upon him) gave was that he said: "Two religions will not remain in the Arabian Peninsula."
Imam Ahmad and Imam al-Tabarani (in al-Mu'jam al-Awsat) recorded this narration. Imam Ahmad's narrators are the narrators of the Sahih, except Ibn Ishaq, and he has explicitly stated that he heard it directly. The hadith of Sayyiduna Ali (may Allah be pleased with him) concerning the caliphate, recorded by Imam Ahmad, has already passed.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الجهاد / 9661
Hadith Gradingمحدثین:إسنادہ صحیح۔
Hadith Takhrij«اخرجه الطبراني فى المعجم الاوسط (1070) اخرجه احمد فى المسند (275/6) ، أخرجه مسند أحمد برقم: 25820»