Musannaf Ibn Abi Shayba 9:458

Abu Bakr narrated to us, he said: Ali bin Mushir and Abu Mu'awiyah narrated to us, from Hajjaj, from Abd al-Malik bin Mughirah al-Ta'ifi, from Abd al-Rahman al-Sulmani, the freed slave of Umar, who said: The Messenger of Allah (may Allah bless him and grant him peace) delivered a sermon and said: "Marry off the unmarried among you." A man stood up to him and said: "O Messenger of Allah, what are the ties (al-'ala'iq) between them?" He said: "That which their families agree upon."