Musnad Ahmad 28:521

'Attab narrated to us, 'Abdullah narrated to us, Usamah bin Zayd informed us, from 'Amr bin Shu'ayb, from his father, from 'Abdullah bin 'Amr, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "It is not lawful for a man to separate between two people except with their permission."