Hadith 10:651
Abu Bakr narrated to us, he said: Hushaym narrated to us, from Mughira, he said: I said to Ibrahim, "Is the one who performs *li'an* (invoking curses) more severe than the one who divorces three times?" He said, "Yes."
حدثنا أبو بكر قال نا [ هشيم ] عن مغيرة قال قلت لإبراهيم الملاعن أشد من الذي يطلق ثلاثا فقال نعم