'Therein' in the Bible

Let the sea roar, and the fulness thereof: let the fields rejoice, and all that is therein.

And he brought forth the people that were therein, and cut them with saws, and with harrows of iron, and with axes. And thus did David unto all the cities of the children of Ammon. And David and all the people returned to Jerusalem.

Then David said to Ornan, Grant me the place of this threshingfloor, that I may build an altar therein unto the LORD: thou shalt grant it me for the full price: that the plague may be stayed from the people.