וַיֹּ֣אמֶר אַבְרָ֔ם הֵ֣ן לִ֔י לֹ֥א נָתַ֖תָּה זָ֑רַע וְהִנֵּ֥ה בֶן־בֵּיתִ֖י יוֹרֵ֥שׁ אֹתִֽי׃
And Abram said: ‘Behold, to me Thou hast given no seed, and, lo, one born in my house is to be mine heir.’
Read halakhic rulings (Jewish law) on Genesis 15:3: and classical halakhic sources.