Rashi: If you will do so, your lack will come. Something that you are poor from it, it will come to you immediately, like one who goes quickly. Your lack will come and be full.

Malbim: When he becomes impoverished, poverty comes like a visitor going on his way with no one to stop him. The Atzel does not do anything against the poverty that comes upon him.

Rashi: He comes quickly to protect his master.

Malbim: Afterwards, he lacks food and all his needs. Then he stands and fights against deficiency, and wants to expel it from his house. However, deficiency stands against him like a man bearing a shield. He cannot expel him from his house or do anything to him.