Musnad Ahmad 25159

Translation

✧ I asked Aisha how many units of voluntary prayers did the Messenger of Allah ﷺ used to offer. She said, "He used to offer four units, then three, then six, then three, then eight, then three, then ten, then three. He would not exceed thirteen units, nor would he offer less than seven. He would also never abandon the two units (sunnah) before the dawn prayer."

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