2 Samuel 5:17

But when the Philistines heard that they had anointed David
king over Israel
That the civil war in the nation was now at an end, which they hoped would have issued in their destruction, and therefore lay still and quiet; but now being united under the government of David, and he hereby greatly strengthened and become powerful; and hearing also of his success against Jerusalem, and the friendship he had contracted with Hiram king of Tyre, they thought it was high time to bestir themselves, and put a stop to his power and greatness; and now it was, as Kimchi thinks, that David penned the second psalm, which begins, "why do the Heathen rage" ( Psalms 2:1-12 ) ,

all the Philistines came up to seek David:
in order to fight him, all the five principalities of the Philistines combined together against him; perhaps his old friend Achish king of Gath was now dead, or had now entertained a different opinion of him:

and David heard [of it];
that they had invaded his kingdom, and sought to fight him:

and went down to the hold;
some fortified place or strong hold near Jerusalem, which lay lower than the city, or than the strong hold of Zion, in which David dwelt; hither he went, not so much for safety, or with an intention to abide there, but as a rendezvous for his men, and to prepare to meet the Philistines.