'Foothold' in the Bible

and "I won't let Israel's foothold slip on the land that I've given to your ancestors, if only they will be careful to keep everything that I commanded them in the Law, in the statutes, and in the ordinance through Moses."

I have sunk in deep mire, and there is no foothold;I have come into deep waters, and a flood overflows me.

And do not give the devil an opportunity [to lead you into sin by holding a grudge, or nurturing anger, or harboring resentment, or cultivating bitterness].