Came from his insides/ to be a descendant/ to be sprung from someone's loin
In literary style: his offspring; his son; one born from him.
("When your days are fulfilled and you lie with your fathers, I will raise up your seed after you, who shall come from your body, and I will establish his kingdom" — 2 Samuel 7:12, spoken by God to David through the prophet Nathan)
Translation
Expression (Hebrew)
יָצָא מִמֵּעָיו
Definition (Hebrew)
בַּמְּלִיצָה: הוּא הַצֶּאֱצָא שֶׁלּוֹ. בְּנוֹ. נוֹלַד מִמֶּנּוּ.
(" כִּי יִמְלְאוּ יָמֶיךָ וְשָׁכַבְתָּ אֶת אֲבֹתֶיךָ וַהֲקִימֹתִי אֶת זַרְעֲךָ אַחֲרֶיךָ אֲשֶׁר יֵצֵא מִמֵּעֶיךָ וַהֲכִינֹתִי אֶת מַמְלַכְתּוֹ"- שְׁמוּאֵל ב ז יב, ה' לְדָוִד בְּאֶמְצָעוּת נָתָן הַנָּבִיא)