'Thong' in the Bible

And he preached, saying, There comes he that is mightier than I after me, the thong of whose sandals I am not fit to stoop down and unloose.

John answered all, saying, I indeed baptise you with water, but the mightier than I is coming, the thong of whose sandals I am not fit to unloose; he shall baptise you with the Holy Spirit and fire;

he who comes after me, the thong of whose sandal I am not worthy to unloose.