Musannaf Ibn Abi Shayba 13:2132

Abu Bakr narrated to us, he said: Ibn Abi Za'idah narrated to us, from Layth, from Abu al-Khattab, from Abu Zur'ah, from Abu Idris, from Thawban, who said: The Messenger of Allah (may Allah bless him and grant him peace) cursed the one who offers the bribe, the one who takes the bribe, and the intermediary—meaning the one who walks between them.