Muwatta Malik, Book 2, Hadith 132 (In-Book)

Yahya related to me from Malik that he asked Ibn Shihab about a pregnant woman who noticed bleeding. Ibn Shihab replied, "She refrains from prayer." Yahya said that Malik said, "That is what is done in our community."

وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ سَأَلَ ابْنَ شِهَابٍ عَنِ الْمَرْأَةِ الْحَامِلِ، تَرَى الدَّمَ قَالَ تَكُفُّ عَنِ الصَّلاَةِ، ‏.‏ قَالَ يَحْيَى قَالَ مَالِكٌ وَذَلِكَ الأَمْرُ عِنْدَنَا ‏.‏

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also referenced under: Book 2, Hadith 103 (USC-MSA)