Histories

This was Gobryas' advice, and at nightfall Darius followed it. He left the men who were worn out, and those whose loss mattered least to him, there in the camp, and all the asses, too, tethered.

His reasons for leaving the asses, and the infirm among his soldiers, were the following: the asses, so that they would bray; the men, who were left because of their infirmity, he pretended were to guard the camp while he attacked the Scythians with the fit part of his army.

Giving this order to those who were left behind, and lighting campfires, Darius made all haste to reach the Ister. When the asses found themselves deserted by the multitude, they brayed the louder for it; and the Scythians heard them and assumed that the Persians were in the place.