Musnad Ahmad 626:58

Husayn ibn Ali narrated to us, from Ibn Suqah, from Warrad, the freed slave of al-Mughirah ibn Shu’bah, who said: Mu’awiyah wrote to al-Mughirah ibn Shu’bah, "Write to me something you heard from the Messenger of Allah (peace and blessings of Allah be upon him), with no one between you and him." He said: So he dictated to me, and I wrote: I heard the Messenger of Allah (peace and blessings of Allah be upon him) saying: "Indeed, Allah has forbidden three things and prohibited three things. As for the three things that Allah has prohibited: they are 'it is said' and 'he said' (idle gossip), persistent begging, and the wasting of wealth."