Exegetical and Hermeneutical Commentary of Genesis 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.

Verse 9. 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.

Fuente: Adam Clarke’s Commentary and Critical Notes on the Bible

Two things are here noted:

1. The sin itself, which is here particularly described by the Holy Ghost, that men might be instructed concerning the nature and the great evil of this sin of self-pollution, which is such that it brought upon the actor of it the extraordinary vengeance of God, and which is condemned not only by Scripture, but even by the light of nature, and the judgment of heathens, who have expressly censured it as a great sin, and as a kind of murder. Of which see my Latin Synopsis. Whereby we may sufficiently understand how wicked and abominable a practice this is amongst Christians, and in the light of the gospel, which lays greater and stricter obligations upon us to purity, and severely forbids all pollution both of flesh and spirit.

2. The cause of this wickedness; which seems to have been either hatred of his brother, or envy at his brothers name and honour, springing from the pride of his own heart.

Fuente: English Annotations on the Holy Bible by Matthew Poole

And Onan knew that the seed should not be his,…. Should not be called a son of his, but a son of his brother Er; this is to be understood only of the firstborn; all the rest of the children born afterwards were reckoned the children of the real parent of them; this shows this was a custom in use in those times, and well known, and was not a peculiar case:

and it came to pass, when he went in unto his brother’s wife; to cohabit with her, as man and wife, he having married her according to his father’s direction:

that he spilled [it] on the ground, lest he should give his seed to his brother: lest his brother’s wife he had married should conceive by him, and bear a son that should be called his brother’s, and inherit his estate; and this is the sin, which from him is called Onania, a sin condemned by the light of nature, as well as by the word of God, and very prejudicial to mankind, as well as displeasing to God, as follows:

Fuente: John Gill’s Exposition of the Entire Bible

Reader! pause over this history. Who shall take upon him to say, to what extent this unnatural sin hath been prevalent in all ages! Though hidden from human observation, with what malignity must the vast mass of such works of darkness come up before GOD! Oh! how precious, increasingly precious, is JESUS, in every renewed consideration to the mind conscious of sin, whose blood alone cleanseth from all sin.

Fuente: Hawker’s Poor Man’s Commentary (Old and New Testaments)

Gen 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.

Ver. 9. When he went in unto his brother’s wife.] God, for the respect he bears to his own institution of marriage, is pleased to bear with, cover, and not impute many frailties, follies, vanities, wickednesses that are found between man and wife. Howbeit, there is required of such a holy care and conscience, to preserve between themselves, by a conjugal chastity, the marriage bed undefiled; taking heed of an intemperate or intempestive use of it: which by divines, a both ancient and modern, is deemed no better than plain adultery before God. Qui cum uxore sua, quasi eum aliena, concumbit, adulter est, saith that heathen. b Onan’s sin here was self-pollution, aggravated much by his envy that moved him to it, expressed in these words, “lest he should give seed to his deceased brother.” And the more sinful was this sin of his in spilling his seed; because it should have served for the propagation of the Messiah; therefore the Lord slew him: as also, because he was not warned by his brother’s punishment. c

a Intemperans in coniugio, uxoris suae adulter est. – Aug. In uxorem alienam omnis amor turpis est, in suam vero nimius. – Hieron.

b Seneca.

c Hebraei inquiunt perinde ut homicidam, reum esse qui temere semen profundit. – Mercer., in loc.

Fuente: John Trapp’s Complete Commentary (Old and New Testaments)