(Heb., aqar, to hamstring an animal). God commanded Joshua to hamstring the Canaanite horses (Jos 11:6, Jos 11:9). David hamstrung the horses of Hadad-ezer, the king of Zobah (2Sa 8:4; 1Ch 18:4). This was a very cruel practice, justified only by dire military necessity.
Source: Hispanic World Bible Dictionary
Action of cutting the hock (tendons in the leg) of an animal. King †¢Jabin fought against Israel †œwith many horses and war chariots…. But Jehovah said to Joshua … you shall hamstring their horses…† (Jos 11:1-6). When defeating an enemy, they took their horses and d. In this way the animal was weakened, making it useless for war purposes. †œD. David the horses of all the chariots† of Hadad-ezer, king of Zoba (2Sa 8:4; 1Ch 18:4). The same thing was also done to the bulls (Gen 49:6).
Source: Christian Bible Dictionary
This term is used to designate the action of cutting the tendons by the hock (articulation of the hind legs of quadrupeds), and thus disable the animal for work or war. The arbitrariness of two of Jacob’s sons, Simeon and Levi, consisted in having hamstrung bulls, surely when they took revenge on Shechem in the Hivites. (Ge 49:5, 6) The Israelites hamstrung the horses of their enemies in time of war, and on one occasion Jehovah specifically commanded Joshua to do so. (Jos 11:6, 9; 2Sa 8:3, 4; 1Ch 18:3, 4) This was the simplest method of disabling horses for battle, after which they were killed and chariots destroyed . By not seizing the horses of their enemies to use in warfare, the Israelites avoided falling into the trap of relying on that resource rather than relying on Jehovah for protection. (Compare De 17:16; Isa 31:1, 3.)
Source: Dictionary of the Bible