Musar sur Les Nombres 22:9

Rashi already draws attention to the fact that both in Genesis when G–d asked Adam where he was, and when He asked Cain where his brother Abel was, as well as when He appeared to Bileam asking who the men were who had come from Balak, it was not because G–d did not know, but the introductory remarks only served G–d as a pretext to enter into a dialogue with these people. All of this reinforces the question as to why G–d should have employed an endearing term such as ויקרא. This is why the Midrash had to answer that there was no disgrace in speaking to one's tenant.