The Geneva Bible Translation Notes, [1599], at sacred-texts.com
(a) Moses describes the genealogy of Judah, because the Messiah should come from him.
And Judah saw there a daughter of a certain Canaanite, whose name [was] Shuah; (b) and he took her, and went in unto her.
(b) A relationship which nonetheless was condemned by God.
And Judah said unto Onan, Go in unto thy brother's wife, and marry her, and raise (c) up seed to thy brother.
(c) This order was for the preservation of the stock, since the child begotten by the second brother would have the name and inheritance of the first: a practice which is abolished in the New Testament.
Then said Judah to Tamar his daughter in law, (d) Remain a widow at thy father's house, till Shelah my son be grown: for he said, Lest peradventure he die also, as his brethren [did]. And Tamar went and dwelt in her father's house.
(d) For she could not marry in any other family so long as Judah would retain her in his.
And he turned unto her by the way, and said, Go to, I pray thee, let me come in unto thee; (for he (e) knew not that she [was] his daughter in law.) And she said, What wilt thou give me, that thou mayest come in unto me?
(e) God miraculously blinded him so that he could not know her by her voice.
And Judah sent the kid by the hand of his (f) friend the Adullamite, to receive [his] pledge from the woman's hand: but he found her not.
(f) That his wickedness might not be known to others.
And Judah said, Let her take [it] to her, lest we be (g) shamed: behold, I sent this kid, and thou hast not found her.
(g) He fears man more than God.
And it came to pass about three months after, that it was told Judah, saying, Tamar thy daughter in law hath played the harlot; and also, behold, she [is] with child by whoredom. And Judah said, Bring her forth, and let her be (h) burnt.
(h) We see that the Law, which was written in man's heart, taught them that adultery should be punished with death, even though no law had been given yet.
And Judah acknowledged [them], and said, She hath been (i) more righteous than I; because that I gave her not to Shelah my son. And he knew her again (k) no more.
(i) That is, she ought rather to accuse me than I her.
(k) for the horror of the sin condemned him.
And it came to pass, as he (l) drew back his hand, that, behold, his brother came out: and she said, How (m) hast thou broken forth? [this] breach [be] upon thee: therefore his name was called Pharez.
(l) Their heinous sin was signified by this monstrous birth.
(m) Or the separation between you and your brother.