New Living Translation
But Onan was not willing to have a child who would not be his own heir. So whenever he had intercourse with his brother’s wife, he spilled the semen on the ground. This prevented her from having a child who would belong to his brother.

American Standard Version
And Onan knew that the seed would 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 he should give seed to his brother.

Berean Study Bible
But Onan knew that the offspring would not belong to him; so whenever he would sleep with his brother’s wife, he would spill his seed on the ground so that he would not produce offspring for his brother.

Douay-Rheims Bible
He knowing that the children should not be his, when he went in to his brother's wife, spilled his seed upon the ground, lest children should be born in his brother's name.

English Revised Version
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 he should give seed to his brother.

King James Bible
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.

World English Bible
Onan knew that the seed wouldn't be his; and it happened, when he went in to his brother's wife, that he spilled it on the ground, lest he should give seed to his brother.

Young's Literal Translation
and Onan knoweth that the seed is not reckoned his; and it hath come to pass, if he hath gone in unto his brother's wife, that he hath destroyed it to the earth, so as not to give seed to his brother;

Genesis 38:9 Additional Translations ...