Leviticus 1:1 And He called to Moses, and God spoke to him from the Tent of Meeting saying
Gemora Yoma 4b: And He called to Moses, and God spoke to him; why does Scripture mention the call before the speech? — The Torah teaches us good manners: a man should not address his neighbor without having first called him.
Torah Temimah Colloquial Translation on Note #1:
In other words, one should not begin to speak [to one’s friend] suddenly. The reason for this is to allow the listener [some time] to prepare himself to listen. This is similar to what it writes in Gemora Nidda 16b that God hates one who enters the house of his friend suddenly. Further, in Meseket Derek Eretz, Chapter 5, it says that one should learn proper behavior from God. God stood outside the Garden of Eden and He called to Adam, as the posuk says (Genesis 3:9) “And God called to the man [Adam] and He said, Where are you”.
The reason why our Gemora quotes our posuk here [in Leviticus] instead of the posuk in Genesis, is perhaps because the Gemora wanted to learn the greatest lesson. Even with someone who God recognized and brought close to Himself with the greatest love and affection [such as Moses], God nevertheless [displays good manners and proper behavior] by not suddenly beginning to speak with him. It is about Moses that God testifies and says “in all My house he is faithful” and “plainly and not in riddles do I speak to him.” Even here He prepared him [Moses] to speak before He spoke with him.
Editor’s Note: The Torah Temimah wants to emphasize, I think, that even God displays proper manners and proper behavior. Further, this proper behavior should be towards everyone, even someone whom you love dearly and with whom you are very familiar