When the time came for her to give birth, there were twins in her womb! While she was in labor, one of them put out his hand, and the midwife tied a crimson thread on that hand, to signify: This one came out first. But just then he drew back his hand, and out came his brother; and she said, “What a breach you have made for yourself!” So he was named Perez. Afterward his brother came out, on whose hand was the crimson thread; he was named Zerah.

Genesis 38:27-30