After Abraham sent Ishmael away into the wilderness with his mother Hagar, the patriarch did not forget his firstborn son. According to Pirkei de Rabbi Eliezer and the Midrash Hagadol on Genesis, Abraham visited Ishmael's home on two separate occasions — and each visit became a test of character.
The first time Abraham came, Ishmael was not home. His wife answered the door. Abraham, who did not identify himself, asked for food and water. The wife refused. She complained bitterly about her life — about the hardships of the desert, about Ishmael's absences, about the poverty they endured. She offered the old stranger nothing. Not even a cup of water.
Abraham left without revealing who he was. But he left a message for Ishmael: "Tell your husband that an old man came by and said to change the threshold of his house." Ishmael understood immediately. The "threshold" was his wife. He divorced her and married another woman.
Some time later, Abraham returned. Again, Ishmael was away. But the new wife received Abraham with warmth and generosity. She brought him food and drink, offered him shade and rest, and treated the unknown stranger with the dignity that the Torah demands for every guest. She did not complain about her circumstances. She spoke well of her husband.
Abraham left a second message: "Tell your husband that the threshold of his house is good. Let him keep it." When Ishmael heard these words, he understood that his father had approved of his new wife.
The tale was told across Jewish communities as a lesson in hakhnasat orchim (הכנסת אורחים), the sacred duty of hospitality. A person's true character is revealed not in how they behave before important people, but in how they treat a stranger at the door. Abraham's test was simple but devastating: the first wife failed, the second passed, and the difference determined the course of a family's destiny.