'Firm' in the Bible

The priests who bore the ark of the covenant of Yahweh stood firm on dry ground in the middle of the Jordan; and all Israel passed over on dry ground, until all the nation had passed completely over the Jordan.

and command them, saying, 'Take from out of the middle of the Jordan, out of the place where the priests' feet stood firm, twelve stones, and carry them over with you, and lay them down in the lodging place, where you will lodge tonight.'"