The Mosaic law taught “If brethren dwell together, and one of them die, and have no child, the wife of the dead shall not marry without unto a stranger: her husband’s brother shall go in unto her, and take her to him to wife, and perform the duty of an husband’s brother unto her. And it shall be, that the firstborn which she beareth shall succeed in the name of his brother which is dead, that his name be not put out of Israel” (Deuteronomy 25:5-6).
So, according to the Mosaic marriage law, Tamar was given in marriage to Er’s brother, Onan. But “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. And the thing which he did displeased the LORD: wherefore he slew him also” (Genesis 28:9,10).
Onan did not want to share his inheritance with his brother’s offspring, so he spilled his seed on the ground. But “What he did was wicked in the LORD’s sight; so He put him to death also.” Onan was selfish. He used Tamar for his own pleasure, but refused to do his legal duty of creating a seed for his brother.
In His service,