Sa'id bin al-Musaiyab regarding a man who finds nothing to spend on his wife:
"They are to be separated."
Reported by Sa'id bin Mansur, from Sufyan, from Abu az-Zinad, from Sa'id bin al-Musaiyab. He said, "I asked Sa'id (bin al-Musaiyab), 'Is this Sunnah?' And he replied, 'Yes, it is Sunnah!'"
[This Hadith is a strong Mursal (missing link after the Tabi'i].