Musnad Ahmad 30:3032

Waki’ narrated to us, he said: Ibn Abi Dhi’b and Hajjaj narrated to us, he said: Ibn Abi Dhi’b informed us, from Sa’id al-Maqburi, from Abu Hurairah, he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "You will be eager for leadership, and it will become a source of regret and remorse—Hajjaj said: on the Day of Resurrection. How excellent is the wet nurse, and how wretched is the weaner."