The Prophet ﷺ said, "We are an unlettered nation. We neither write nor calculate. The month is like this and like this," until he mentioned twenty-nine.Ishaq said that he clapped his hands together three times, holding back his thumb on the third time.
حدثنا عبد الرحمن عن سفيان وإسحاق يعني الأزرق قال حدثنا سفيان عن الأسود بن قيس عن سعيد بن عمرو
عن النبي ﷺ قال إنا أمة أمية لا نكتب ولا نحسب الشهر هكذا وهكذا حتى ذكر تسعا وعشرين قال إسحاق وطبق يديه ثلاث مرات وحبس إبهامه في الثالثة
Its isnad is sahih, and it is a repetition of 5017, see also 5039. Saeed bin Amr is Saeed bin Amr bin Saeed bin As. In H it appears as "Saeed bin Umar," which is an error, we have corrected it from K and M.