Musnad Ahmad 37:0

Narrated to us by Abd al-Rahman, from Sufyan, from Habib ibn Abi Thabit, from Abd Allah ibn al-Bab, from Sabrah ibn Ma’bad al-Juhani, that the Messenger of Allah (ﷺ) said: "O people, I had permitted you to engage in temporary marriage (mut'ah) with women. But indeed, Allah has prohibited that until the Day of Resurrection. So whoever has any of them with him, let him release her, and do not take back anything of what you have given them."