Quintus Curtius Rufus, History of Alexander 8.14.38

8.14.38

Iam Alexander consecutus erat et pertinacia Pori cognita vetabat resistentibus parci. Ergo undique et in pedites et in ipsum Porum tela congesta sunt, quis tandem gravatus labi ex belua coepit.

Alexander had now come up, and knowing how obstinate Porus was, forbade quarter to be given to those who resisted. The infantry therefore, and Porus himself, were assailed with darts from all points, and as he could no longer bear up against them he began to slip from his elephant. The Indian driver, thinking the king wished to alight, made the elephant kneel down in the usual manner. On seeing this the other elephants also knelt down, for they had been trained to lower themselves when the royal elephant did so. Porus and his men were thus placed entirely at the mercy of the conqueror. Alexander, supposing that he was dead, ordered his body to be stripped, and men then ran forward to take off his breastplate and robes, when the elephant turned upon them in defence of its master, and lifting him up placed him once more on its back. Upon this the animal was on all sides overwhelmed with darts, and when it was stabbed to death, Porus was placed upon a waggon. But the king perceiving him to lift up his eyes, forgot all animosity, and being deeply moved with pity, said to him, "What the plague! what madness induced you to try the fortune of war with me, of whose exploits you have heard the fame, especially when in Taxiles you had a near example of my clemency to those who submit to me?" He answered thus: "Since you propose a question, I shall answer with the freedom which you grant by asking it.