Siman 244

(4.) Once Rabbainu o.b.m. told me by way of complaint about the immensity of the sufferings he has — saying he is compelled to think of Balaam in his mind every day within his prayer. And he told no more. And what is understood from his words plainly: that every day during prayer he must subdue the wicked Balaam — to nullify his impurity from the world.