And after this, a war broke out at Gezer with the Philistines. At that time Sibbecai the Hushathite killed Sippai, one of the descendants of the Rephaites, and they were subdued.

“the Rephaites.” The Rephaites were Nephilim, the “Fallen Ones.”
[For more on the Nephilim, see commentary on Gen. 6:4.]