Genesis 38:9-10
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Onan’s refusal to give his brother offspring wasn’t just about avoiding fatherhood; it was a deliberate act to erase his brother's lineage and legacy. The text highlights that he “knew the offspring would not be his” in terms of inheritance and name, revealing a calculated defiance of familial and divine order.
But Onan knew that the offspring would not be his. So whenever he went in to his brother’s wife he would waste the semen on the ground, so as not to give offspring to his brother. And what he did was wicked in the sight of the LORD, and he put him to death also.
English Standard Version (ESV)
This passage is part of the story of Judah, one of Jacob's sons, detailing a significant family crisis. After his firstborn, Er, dies without heirs, Judah instructs his second son, Onan, to perform the duty of a brother-in-law by marrying Er's widow, Tamar, to produce an heir for his deceased brother. This directive comes after Judah's wife also dies, and he is preparing to shear sheep, an event that indirectly leads to Tamar's deception of Judah himself.
Why was Onan obligated to sleep with his brother's wife? It wasn't just about keeping the family name alive; it was about the very identity and inheritance of that lineage.
The custom described here, later formalized as the Levirate Law, was crucial in ancient Israelite society.
The Core Obligation:
When a man died without an heir, his brother was obligated to marry the widow. The first son born from this union would legally be considered the son of the deceased brother, carrying on his name and inheriting his property.
More Than Just Names:
This wasn't merely an administrative detail. It was about ensuring the continuity of families, land inheritance, and the overall covenantal promises God had made to Abraham and his descendants. To refuse this was to deny a man his place in the lineage and potentially disrupt God's redemptive plan.
Onan's act was more than just a physical act; it was a profound act of rebellion against God's design for family and inheritance. What made his 'spilling his seed' so offensive?
Onan's action wasn't an accident; it was a calculated decision to thwart God's will and his brother's legacy.
The Act Itself:
Scripture states he 'wasted the semen on the ground.' This refers to the practice of withdrawal during intercourse, specifically to prevent conception. This was not a minor infraction but a deliberate act of self-interest over covenantal duty.
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The Reason for Displeasure:
God's displeasure stemmed from multiple layers:
While Onan's sin is stark, the story doesn't end there. Judah's actions and Tamar's subsequent choices reveal a complex web of sin, deception, and even divine providence.
The narrative surrounding Onan’s sin is deeply intertwined with the failures of Judah and the resourcefulness of Tamar.
Judah’s Failure:
Judah, the father, failed in his responsibility. He initially promised Tamar to his youngest son, Shelah, but then withheld her, fearing for Shelah’s life after his older sons died. This was a failure to trust God and a dereliction of his duty to his daughter-in-law, leaving her in a precarious and vulnerable position.
Tamar's Desperate Act:
Left in a state of uncertainty and facing potential destitution, Tamar took matters into her own hands. Disguising herself as a prostitute, she ingeniously secured a pledge from Judah himself. This act, while morally compromised, was driven by a desire to secure her future and to provoke Judah into fulfilling his obligation, ultimately leading to the birth of twins, Perez and Zerah.
Divine Providence:
Despite the sin and deception on all sides, God’s hand is evident. The lineage from which Jesus would eventually come was preserved through these very complicated and flawed human actions. The story, though uncomfortable, demonstrates that God can work through imperfect people and circumstances to bring about His redemptive purposes.
Onan's refusal to fulfill the ancient custom of levirate marriage by intentionally preventing conception was not merely a social or familial issue, but a profound offense against God's command and the sanctity of life and lineage. The text emphasizes that this act was seen as destroying potential life and defying God's plan for family continuity.
c. 1700s-1600s BC
Judah's Marriage and Sons
Judah, son of Jacob, marries a Canaanite woman and has three sons: Er, Onan, and Shelah. This union itself is noted as problematic due to marrying outside the covenant family.
c. 1700s-1600s BC
Er's Wickedness and Death
Judah's firstborn, Er, commits wickedness displeasing to the Lord and is put to death by God. This event sets the stage for the next action.
c. 1700s-1600s BC— this verse
Onan's Refusal of Levirate Marriage
Judah instructs his second son, Onan, to marry Er's widow, Tamar, and father a child for Er to carry on his name. Onan intentionally prevents conception by spilling his semen on the ground, an act that deeply offends God.
c. 1700s-1600s BC
Onan's Death
Because of his sinful act, the Lord strikes Onan dead as well. This leaves Tamar a widow in her father-in-law's house with no living husband or sons.
c. 1700s-1600s BC
Judah's Deception of Tamar
Judah, fearing his youngest son Shelah would also die, promises Tamar to him but fails to give her to Shelah when he grows up. Tamar, left childless and deceived, takes matters into her own hands.
c. 1700s-1600s BC
Tamar's Deception of Judah
Disguised as a prostitute, Tamar seduces Judah himself, conceiving twins. Judah, recognizing his own signet and staff later, acknowledges his wrongdoing.
c. 1700s-1600s BC
Birth of Perez and Zerah
Tamar gives birth to twins, Perez and Zerah. The lineage of the Messiah would come through Perez, highlighting God's redemptive plan even amidst human sin and brokenness.
This Levitical law explicitly forbids having sexual relations with a brother's wife, directly addressing the practice known as the levirate marriage, which Onan was technically supposed to uphold but perverted.
Deuteronomy 25:5-6This passage establishes the law of the levirate marriage, requiring a brother to marry his deceased brother's childless widow to preserve the brother's name. Onan's act directly violated the spirit and intent of this commandment.
Proverbs 6:32-33While not mentioning Onan directly, this proverb speaks to the deep dishonor and severe consequences of adultery, paralleling the grievous sin and divine judgment Onan faced for his destructive actions.
1 Corinthians 6:18-20This New Testament passage calls believers to flee sexual immorality and honor God with their bodies, providing a broader theological framework that condemns the self-serving and destructive sexual acts exemplified by Onan.
clarkeGenesis 38:9: "And Onan knew that the seed should not be his; and it came to pass, when he went in unto his brother's wife, that he spilled it on the ground, lest that he should give seed to his brother."
Onan knew that the seed should not be his - That is, that the child begotten of his brother's widow should be reckoned as the child of his deceased brother, and his name, though the real father of it, should not appear in the genealogical tables.
calvinGenesis 38:1-30: "And it came to pass at that time, that Judah went down from his brethren, and turned in to a certain Adullamite, whose name was Hirah."
Then said Judah to Tamar his daughter in law, Remain a widow at thy father's house, till Shelah my son be grown: for he said, Lest peradventure he die also, as his brethren did. And Tamar went and dwelt in her father's house.
Et dixit Jehudah ad Thamar nurum suam, Mane vidua in domo patris tui, donec crescat Selah filius meus: dicebat…
Onan’s refusal to give his brother offspring wasn’t just about avoiding fatherhood; it was a deliberate act to erase his brother's lineage and legacy. The text highlights that he “knew the offspring would not be his” in terms of inheritance and name, revealing a calculated defiance of familial and divine order.
This passage is part of the story of Judah, one of Jacob's sons, detailing a significant family crisis. After his firstborn, Er, dies without heirs, Judah instructs his second son, Onan, to perform the duty of a brother-in-law by marrying Er's widow, Tamar, to produce an heir for his deceased brother. This directive comes after Judah's wife also dies, and he is preparing to shear sheep, an event that indirectly leads to Tamar's deception of Judah himself.
This passage is part of the story of Judah, one of Jacob's sons, detailing a significant family crisis. After his firstborn, Er, dies without heirs, Judah instructs his second son, Onan, to perform the duty of a brother-in-law by marrying Er's widow, Tamar, to produce an heir for his deceased brother. This directive comes after Judah's wife also dies, and he is preparing to shear sheep, an event that indirectly leads to Tamar's deception of Judah himself.
"But Onan knew that the offspring would not be his. So whenever he went in to his brother’s wife he would waste the semen on the ground, so as not to give offspring to his brother. And what he did was wicked in the sight of the LORD, and he…" — Onan’s refusal to give his brother offspring wasn’t just about avoiding fatherhood; it was a deliberate act to erase his brother's lineage and legacy. The text highlights that he “knew the offspring…
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Last reviewed October 2026
