כִּ֤י עֶזְרָא֙ הֵכִ֣ין לְבָב֔וֹ לִדְר֛וֹשׁ אֶת־תּוֹרַ֥ת יְהוָ֖ה וְלַעֲשֹׂ֑ת וּלְלַמֵּ֥ד בְּיִשְׂרָאֵ֖ל חֹ֥ק וּמִשְׁפָּֽט׃ (ס)
Rashi on Ezra
For Ezra... Therefore, he went and prospered in his way, because Ezra prepared his heart, etc. He gives a reason for his words.