Biography of Shelah

Genesis 38

2 And Judah saw there a daughter of a certain Canaanite, whose name was Shua; and he took her, and went in unto her.

3 And she conceived and bore a son, and he called his name Er.

4 And she conceived again and bore a son, and she called his name Onan.

5 And she yet again conceived and bore a son, and called his name Shelah. And he was at Chezib when she bore him.

6 And Judah took a wife for Er his firstborn, whose name was Tamar.

7 And Er, Judah's firstborn, was wicked in the sight of the LORD; and the LORD slew him.

8 And Judah said unto Onan, "Go in unto thy brother's wife and marry her, and raise up seed to thy brother."

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 he should give seed to his brother.

10 And the thing which he did displeased the LORD; therefore He slew him also.

11 Then said Judah to Tamar his daughter-in-law, "Remain a widow at thy father's house, until Shelah my son is grown"; for he said, "Lest perhaps he die also, as his brethren did". And Tamar went and dwelt in her father's house.

12 And in process of time, the daughter of Shua, Judah's wife, died; and Judah was comforted, and went up unto his sheepshearers to Timnah, he and his friend Hirah the Adullamite.

13 And it was told Tamar, saying, "Behold, thy father-in-law goeth up to Timnah to shear his sheep."

14 And she put her widow's garments off from her and covered herself with a veil, and wrapped herself, and sat in an open place which is on the way to Timnah; for she saw that Shelah was grown, and she was not given unto him as wife.

From Jewish Encyclopedia, by Wilhelm Bacher and Jacob Zallel Lauterbach:

Youngest son of Judah by the daughter of the Canaanite Shuah; born in Chezib in the shephelah of Judah. His extreme youth at the time of the death of his brother Onan was the ostensible excuse alleged by his father for the refusal to permit him to marry his sister-in-law Tamar (Gen. xxxviii. 5-12). Shelah became the ancestor of many families (I Chron. iv. 21-23), as had been betokened, according to rabbinical interpretation, by his name (Gen. R. lxxxv. 5).