Musnad Ahmad 626:59

Hashim narrated to us, he said: More than one person informed us, among them al-Mughirah, from al-Sha’bi, from Warrad, the scribe of al-Mughirah ibn Shu’bah, that Mu’awiyah wrote to al-Mughirah ibn Shu’bah: "Write to me with a hadith you heard from the Messenger of Allah, may Allah bless him and grant him peace." He said: So al-Mughirah wrote to him that he heard him saying upon finishing his prayer: "There is no god but Allah alone, He has no partner; to Him belongs the dominion, and to Him belongs the praise, and He is capable of all things," three times. And he used to forbid "he said and they said" (gossip), excessive questioning, wasting wealth, withholding and demanding (stinginess), disobedience to mothers, and the burying of daughters alive.