Rabbi Yochanan said in the name of Rabbi Shimon ben Yochai: From the day the Holy One, blessed be He, created the world, there was no person who called the Holy One, blessed be He, "Master," until Abraham came and called Him "Master," as it is said, "And he said, O Lord [Adonai] GOD" (Genesis 15:8). And even Daniel was answered only by the merit of Abraham, as it is said, "And cause Your face to shine upon Your desolate sanctuary, for the Lord's [Adonai's] sake" (Daniel 9:17). It should have said "for Your own sake," but rather "for the sake of Abraham," who called Him "Master."
Abraham Was the First Person Ever to Call God Master
Yalkut Shimoni on Torah 77:8
אָמַר רַבִּי יוֹחָנָן מִשּׁוּם רַבִּי שִׁמְעוֹן בֶּן יוֹחָאי, מִיּוֹם שֶׁבָּרָא הַקָּדוֹשׁ בָּרוּךְ הוּא אֶת הָעוֹלָם, לֹא הָיָה אָדָם שֶׁקְּרָאוֹ לְהַקָּדוֹשׁ בָּרוּךְ הוּא אָדוֹן, עַד שֶׁבָּא אַבְרָהָם וּקְרָאוֹ אָדוֹן, שֶׁנֶּאֱמַר, (לעיל פסוק ח) וַיֹּאמֶר אֲדֹנָי אֱלֹהִים וְגוֹ' וְאַף דָּנִיאֵל לֹא נַעֲנָה אֶלָּא בִּזְכוּת אַבְרָהָם, שֶׁנֶּאֱמַר, (דניאל ט, יז) "וְהָאֵר פָּנֶיךָ עַל מִקְדָּשְׁךָ הַשָּׁמֵם לְמַעַן אֲדֹנָי", לְמַעֲנְךָ מִבָּעֵיה לֵיהּ, אֶלָּא לְמַעַן אַבְרָהָם שֶׁקְּרָאוֹ אָדוֹן.