Musannaf Ibn Abi Shayba 33:384

Abu Mu'awiyah narrated to us, from al-A'mash, from Khaythama, who said: Abu al-Darda' said: I was a merchant before Muhammad, may Allah bless him and grant him peace, was sent. When Muhammad was sent, I attempted [to combine] trade and worship, but they did not come together. So I took to worship and left trade.