Bulugh al-Maram, Book 1, Hadith 46 (In-Book)

In another verson of Abu Da’ud is: “If you perform ablution rinse your mouth”.

وَلِأَبِي دَاوُدَ فِي رِوَايَةٍ: { إِذَا تَوَضَّأْتَ فَمَضْمِضْ } (51)‏.‏ ‏2 ‏- صحيح.‏ سنن أبي داود (144)‏.‏

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also referenced under: Book 1, Hadith 45 (English)