For by thee I have run through a troop. The military key-note is at once struck. Gedud ( גְּדוּד) is a marauding band of light-armed troops sent out to plunder an enemy's country. David "ran through" such a "troop," when he pursued and defeated the Amalekites who had plundered and burnt Ziklag (1 Samuel 30:17).
It is called three times a gedud (Psalms 18:8 and Psalms 18:15 twice). And by my God have I leaped over a wall. Shur ( שׁוּר) is a rare word for "wall," occurring in the Hebrew text only here and in Genesis 49:22, though used also of the walls of Jerusalem in the Chaldee of Ezra (Ezra 4:12, Ezra 4:13, Ezra 4:16).
It may designate the walls of Jerusalem in this place, and David may intend to allude to his conquest of the stronghold of Zion from the Jebusites (2 Samuel 5:6, 2 Samuel 5:7).