the thong or fastening by which the sandal was attached to the foot. It occurs int he proverbial expression in (Genesis 14:23) and is there used to denote something trivial or worthless. Another semi-proverbial expression in (Luke 3:16) points to the fact that the office of bearing and unfastening the shoes of great personages fell to the meanest slaves.

John i. 35-37
... And observe, I pray you, this, how, when he said, "He that cometh after me is preferred
before me"; and that, "I am not worthy to unloose the lachet of His shoe ...
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Lachet

Latch