What is written just above this matter? "And it shall be, when he sins and is guilty, that he shall restore the stolen thing" (Leviticus 5:23-26), and afterward, "This is the Torah of the burnt offering." If you sought to bring an offering, do not rob any person of anything. Why? "For I the LORD love justice, I hate robbery in a burnt offering" (Isaiah 61:8). And when do you bring up a burnt offering and I accept it? When you have cleansed your hand of robbery. David said, "Who shall ascend the mountain of the LORD, and who shall stand in His holy place? He who has clean hands and a pure heart" (Psalms 24:3-4). And from the very beginning of the offerings you learn it: "A person who brings near from among you" (Leviticus 1:2). The Holy One, blessed be He, said: when you bring an offering before Me, be like Adam the first man, who did not rob from others, for he was alone in the world.
Return What You Stole Before You Bring an Offering
Yalkut Shimoni on Torah 480:2
מַה כְּתִיב לְמַעְלָה מִן הָעִנְיָן (ויקרא ה, כו) "וְהָיָה כִּי יֶחֱטָא וְאָשֵׁם וְהֵשִׁיב אֶת הַגְּזֵלָה", וְאַחַר כָּךְ זֹאת תּוֹרַת הָעֹלָה, אִם בִּקַּשְׁתָּ לְהַקְרִיב קָרְבָּן לֹא תִגְזֹל לְאָדָם כְּלוּם, לָמָּה (ישעיה סא, ח) "כִּי ה' אֹהֵב מִשְׁפָּט שׂנֵא גָּזֵל בְּעֹלָה", וְאֵימָתַי אַתָּה מַעֲלֶה עוֹלָה וַאֲנִי מְקַבְּלָהּ כְּשֶׁתְּנַקֶּה יָדְךָ מִן הַגָּזֵל. אָמַר דָּוִד "מִי יַעֲלֶה בְהַר ה' וּמִי יָקוּם בִּמְקוֹם קָדְשׁוֹ נְקִי כַפַּיִם וּבַר לֵבָב". וּמִתְחִלַּת הַקָּרְבָּנוֹת אַתָּה לָמֵד (ויקרא א, ב) "אָדָם כִּי יַקְרִיב מִכֶּם", אָמַר הַקָּדוֹשׁ בָּרוּךְ הוּא כְּשֶׁתְּהֵא מַקְרִיב לְפָנַי תְּהֵא כְּאָדָם הָרִאשׁוֹן שֶׁלֹּא הָיָה גּוֹזֵל מֵאֲחֵרִים שֶׁהוּא הָיָה יְחִידִי בָּעוֹלָם.