Muwatta Malik, Book 29, Hadith 1245 (In-Book)

Yahya related to me from Malik that he had heard that Said ibn al-Musayyab said, "If a man does not find the means to spend on his wife, they are to be separated. " Malik said, "That is what I saw the people of knowledge in our city doing." 29.30 Idda of Widows when Pregnant

وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ سَعِيدَ بْنَ الْمُسَيَّبِ، كَانَ يَقُولُ إِذَا لَمْ يَجِدِ الرَّجُلُ مَا يُنْفِقُ عَلَى امْرَأَتِهِ فُرِّقَ بَيْنَهُمَا ‏.‏ قَالَ مَالِكٌ وَعَلَى ذَلِكَ أَدْرَكْتُ أَهْلَ الْعِلْمِ بِبَلَدِنَا ‏.‏

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also referenced under: Book 29, Hadith 82 (USC-MSA)