'Sandal strap' in the Bible

that I will not take a thread or sandal strap or anything that belongs to you, so you can never say, ‘I made Abram rich.’

None of them grows weary or stumbles;no one slumbers or sleeps.No belt is looseand no sandal strap broken.

He is the One coming after me, whose sandal strap I’m not worthy to untie.”