an action came into his hand
The event happened to him. This action happened to come his way.
("And it seems to me that David prayed this prayer after an action of Uriah and Joab came into his hand"—Rashi on Psalms 17:11, and also: "And when an action came into his hand, he did not withhold himself from mockery as in that action with the collector of the charity fund"—Agnon, A Bundle of Stories, 19)
Translation
Expression (Hebrew)
בָּא לְיָדוֹ מַעֲשֶׂה
Definition (Hebrew)
אֵרַע לוֹ הָאֵרוּעַ. הִזְדַּמֵּן לוֹ הַמַּעֲשֶׂה הַזֶּה.
("וְנִרְאֶה לִי שֶׁנִּתְפַּלֵּל דָּוִד תְּפִלָּה זוֹ לְאַחַר שֶׁבָּא לְיָדוֹ מַעֲשֶׂה שֶׁל אוּרִיָּה וְיוֹאָב"-רָשִׁ"י תְּהִלִּים יז יָא, וְכֵן:"וכשבא מַעֲשֶׂה לְיָדוֹ לֹא מֶנַע עַצְמוֹ מִן הליצנות כְּאוֹתוֹ מַעֲשֶׂה בגבאי שֶׁל הַתַּמְחוּי"- עַגְנוֹן/ תכריך שֶׁל סִפּוּרִים, 19)