Avraham Avinu demonstrated his great trust in Hashem, with his willingness to leave his place of birth, and his father’s house, to come to Eretz Yisrael.
He was given many blessings and promises of success, in his holy mission of teaching monotheistic beliefs. All of these promises, ultimately came true, after Avraham successfully overcoming all of his challenges.
At the outset, Hashem reminds him, that he must never forget three things. These were brought in a Mishna in Pirkei Avot. If one remembers three things, he will not come to sin. He must remember, מאין באת, from where he came, ולאן אתה הולך, and to where are you going, ולפני מי אתה עתיד ליתן דין וחשבון, and to whom we will one day, give an accounting.
These were all implied when Avraham was told to leave, ארצך, your land. This was a reminder from where man came and to where he is going. He came from the dust, and will return to the dust. When it says, ממולדתך, from your birthplace, it is a reminder that we were created from a putrid drop. And when it says, מבית אביך, your father’s house, it is a reference to the accounting we will one day give to our Father in Heaven.
In order for Avraham, or anyone, to be successful in their life’s mission, they must not get carried away with themselves. They must never forget their limitations as human beings, and who is really running this world. If he remembers these things, he will receive help from Above, and succeed.