“For I have loved him, because he will instruct his children and his household after him to keep the way of Hashem . . .” (18:19) After all that Avraham did—allowing himself to be thrown into a furnace, leaving his homeland, etc.—the attribute that Hashem loves most about Avraham is that he will instruct his children to keep the way of Hashem!
This demonstrates, says R’ Aryeh Levin z”l (1885-1969; known as the “Tzaddik of Yerushalayim” and as the “Father of the Prisoners” for his role as chaplain of the Yerushalayim prison), that all of Avraham’s and our own tests and challenges are meaningful only if we successfully transmit our beliefs to the ensuing generations. (Brito Le’hodi’am)