Genesis 38:9

Overview - Genesis 38
Judah begets Er, Onan, and Shelah.
Er's marriage with Tamar, and death.
The trespass of Onan.
11 Tamar is reserved for Shelah.
12 Judah's wife dies.
13 Tamar deceives Judah.
27 She bears twins, Pharez and Zarah.
Treasury of Scripture Knowledge

Genesis 38:9  (King James 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 that he should give seed to his brother.

he is
Deuteronomy 25:6 ; Ruth 1:11 ; 4:10

lest that
Job 5:2 ; Proverbs 27:4 ; Titus 3:3 ; James 3:14 James 3:16 ; 4:5