I would say that is a risky proposition. If the water didn't fill the pipe anywhere completely it might be OK but if there's any place where it fills it completely, such as a low corner, it's likely the pipe would crack at that location if it gets cold enough. It only takes one burst pipe to ruin your day! I've seen plumbers use a compressor to blow out the lines to make sure they are empty but depending on the layout of the system it can be tricky. I've also seen them add a valve at the bottom of a system to be able to drain it down reliably.