Genesis 38:28

38:28 While she was giving birth, one child ¹  put out his hand, and the midwife took a scarlet thread and tied it on his hand, saying, “This one came out first.”

Genesis 38:30

38:30 Afterward his brother came out – the one who had the scarlet thread on his hand – and he was named Zerah. ² 

[38:28]  ¹ tn The word “child” has been supplied in the translation for stylistic reasons.

[38:30]  ² sn Perhaps the child was named Zerah because of the scarlet thread. Though the Hebrew word used for “scarlet thread” in v. 28 is not related to the name Zerah, there is a related root in Babylonian and western Aramaic that means “scarlet” or “scarlet thread.” In Hebrew the name appears to be derived from a root meaning “to shine.” The name could have originally meant something like “shining one” or “God has shined.” Zerah became the head of a tribe (Num 26:20) from whom Achan descended (Josh 7:1).