He has it in his power
Figuratively: he is able to do it; it is within his power or ability.
("One who reveals פנים in Torah not according to the law—even though he has Torah and good deeds, he has no share in the world to come"—Avot 3:11; and likewise: "According to the custom in the world... if a man does evil to his fellow, he does not forgive him, and if he has it in his power, he brings him down to his life's end"—Agnon / Takhriḥ shel Sipurim, 172)
Translation
Expression (Hebrew)
יֵשׁ בְּיָדוֹ
Definition (Hebrew)
בְּהַשְׁאָלָה: יֵשׁ בְּכוֹחוֹ. יֵשׁ בְּאֶפְשָׁרוּתוֹ.
("הַמְּגַלֶּה פָּנִים בַּתּוֹרָה שֶׁלֹּא כַהֲלָכָה- אַף עַל פִּי שֶׁיֵּשׁ בְּיָדוֹ תּוֹרָה וּמַעֲשִׂים טוֹבִים אֵין לוֹ חֵלֶק לָעוֹלָם הַבָּא"-אָבוֹת ג יָא, וְכֵן:"בְּנֹהַג שֶׁבָּעוֹלָם...עָשָׂה אָדָם לְרֵעֵהוּ רַע אֵינוֹ מוֹחֵל לוֹ, וְאִם יֵשׁ בְּיָדוֹ יוֹרֵד עִמּוֹ לְחַיָּיו"- עַגְנוֹן/ תַּכְרִיךְ שֶׁל סִפּוּרִים, 172)