To have time for someone is to bring him or her into the sphere of one’s own existence, i.e., the being-in-the-world of one’s Dasein. The result is the formation of a Mitdasein between one and the person that one has time for. How is that time opens up an entry into one’s space? Does this show a primordial relation between time and space, what Heidegger elaborates as time-space (Zeit-Raum) in his secret writings from the 1930s, Contributions to Philosophy (not published until 1989, which is 13 years after his death)?
In contrast, not to have time for someone is to exclude him or her from the being-in-the-world of one’s Dasein – in order to prevent the formation of a Mitdasein with that person.