Combat Stability

 
Prerequisite(s): Combat Focus, Base Attack Bonus 3+, Wis 13+.
 
Benefit: You gain a +4 bonus on checks or rolls to resist bull rush, disarm, grapple, overrun, and trip attempts made against you. If you have three or more combat form feats, the bonus granted by this feat increases to +8.
 
Special: A fighter can select Combat Stability as one of his fighter bonus feats.
 
Source: PHB II