Know that the names of the five days came with the names of number, the beginning of which is Sunday and the end of which is Thursday, and the sixth was designated as the name of Arabism, and in Islam it was designated as Friday, and the seventh was named as Saturday, so they were named by adverb, not by the name of number, just as he swore by the five female slave girls, which are the ones that have the beginning and end, and he did not include with them in this section the sun and the moon, even if They were female slaves, but they were not female. Likewise, Friday and Saturday were days, and their names were not counted among the names of the number.