Then there will be a fourth kingdom as strong as iron; inasmuch as iron crushes and shatters all things, so, like iron that breaks in pieces, it will crush and break all these in pieces. In that you saw the feet and toes, partly of potter's clay and partly of iron, it will be a divided kingdom; but it will have in it the toughness of iron, inasmuch as you saw the iron mixed with common clay. As the toes of the feet were partly of iron and partly of pottery, so some of the kingdom will be strong and part of it will be brittle (Daniel 2:40-42 New American Standard Bible).

And in that you saw the iron mixed with common clay, they will combine with one another in the seed of men Read about it here; but they will not adhere to one anotherRead about it here, even as iron does not combine with pottery (Daniel 2:43).