Musnad Ahmad 435:22

Kathir ibn Hisham narrated to us, he said: Ja'far narrated to us, Yazid ibn al-Asamm narrated to us, he said: I heard Mu'awiyah ibn Abi Sufyan mention a hadith he narrated from the Prophet, may God bless him and grant him peace. I did not hear him narrate any other hadith from the Prophet, may God bless him and grant him peace, except it. That the Prophet, may God bless him and grant him peace, said: "Whoever God intends good for, He grants him understanding of the religion. And a group of Muslims will continue to fight for the truth, prevailing over those who oppose them, until the Day of Resurrection."