He was asked whether the Prophet ﷺ dyed his hair. He replied, "Gray hair did not mar his appearance."
حدثنا محمد بن عبد الله حدثنا حميد
أنه سئل اختضب النبي ﷺ قال لم يشنه الشيب
Its isnad is sahih, it occurred previously at 11993, and his saying "we assumed" here means "we knew."