It is narrated from Abu Al-Zinad, he says: I asked Sa'id bin Al-Musayyib about a man who does not have wealth to spend on his wife, so he said: "Separation will be made between them." Abu Al-Zinad asked: "Is this Sunnah?" Sa'id said: "Yes, it is Sunnah." Imam Shafi'i, may Allah have mercy on him, said: Sa'id's statement that it is Sunnah indicates that it is the Sunnah of the Messenger of Allah, peace and blessings be upon him.
Hadith Referenceمسند الإمام الشافعي / كتاب عشرة النساء والإيلاء والخلع / 1212
Hadith Takhrijصحيح موقوفاً : اخرجه البيهقى 7/ 469 - وفى المعرفة السنن والآثار له (4750)- والدار قطني : 3/ 297 - وعبد الرزاق (12356) وابن ابي شيبة (19006)۔