Is it OK to leave my bicycle unlubricated for a day after a hose-down? I just cleaned my bike with low pressure water but I don't have any lubricant. I left it to dry in my basement with the window left open.

Is there any chance my bike will malfunction or rust before tomorrow when I buy some lubricant?
No, of course not. Having your bike wet and unlibricated for one day won't damage it in any way. Washing it and letting it unlubricated for long period of time will cause you some issues. But one day is not a problem...