ne minä tuon pyhälle vuorelleni ja ilahutan heitä rukoushuoneessani, ja heidän polttouhrinsa ja teurasuhrinsa ovat otolliset minun alttarillani, sillä minun huoneeni on kutsuttava kaikkien kansojen rukoushuoneeksi.
As children, most of us at some point frustrated our mothers into using the phrase “if I've told you once, I've told you a thousand times!” to shut the door, to turn off lights, to put dirty clothes in the hamper, whatever. Our mothers did not, of course, literally mean 1,000 - that would be a lot of telling. They meant that they'd told us to shut the door many, many times, more than they could remember or count, and more than they believe they should have had to.
That's essentially the meaning of "thousand" when used as a standalone number in the Bible. It means much, many, a countless number, a whole era of time, an abundance. And when used in reference to the Lord, it actually means a number greater than that: In those cases it means what is infinite, what is truly without end.