Onan

Onan was the second son of Judah and his Canaanite wife, the daughter of Shua (Genesis 38:4; 1 Chronicles 2:3). After the death of his older brother Er, Judah instructed Onan to marry Er's widow, Tamar, and produce an heir for his brother (Genesis 38:8). However, Onan, knowing that the child would not be his own, practiced coitus interruptus to avoid providing an heir for his brother (Genesis 38:9). This act was displeasing to the Lord, and as a result, God put Onan to death (Genesis 38:10). Onan's death left Tamar without an heir and set the stage for the unusual events that followed, which ultimately led to the birth of Perez and Zerah, twin sons of Judah and Tamar (Genesis 38:27–30). Onan is also mentioned in the genealogies of Judah (Genesis 46:12; Numbers 26:19; 1 Chronicles 2:3).