וַיָּ֧קָם יְהוֹנָתָ֛ן מֵעִ֥ם הַשֻּׁלְחָ֖ן בָּחֳרִי־אָ֑ף וְלֹא־אָכַ֞ל בְּיוֹם־הַחֹ֤דֶשׁ הַשֵּׁנִי֙ לֶ֔חֶם כִּ֤י נֶעְצַב֙ אֶל־דָּוִ֔ד כִּ֥י הִכְלִמ֖וֹ אָבִֽיו׃ (ס)
So Jonathan arose from the table in fierce anger, and did eat no food the second day of the month; for he was grieved for David, and because his father had put him to shame.
Read halakhic rulings (Jewish law) on I Samuel 20:34: and classical halakhic sources.