'Thread' in the Bible

that I will not take a thread nor a shoe-latchet nor aught that is thine, lest thou shouldest say, I have made Abram rich:

And it came to pass, when she travailed, that one put out a hand: and the midwife took and bound upon his hand a scarlet thread, saying, This came out first.

And afterward came out his brother, that had the scarlet thread upon his hand: and his name was called Zerah.