Musnad Ahmad 28:506

Abu Nu'aym narrated to us, Ibn Abi Dhi'b narrated to us, from al-Harith ibn 'Abd al-Rahman, from Abu Salamah, from 'Abdullah ibn 'Amr, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The curse of Allah is upon the one who offers the bribe and the one who takes the bribe."