Frontlets

occurs only in Ex. 13:16; Deut. 6:8, and 11:18. The meaning of
the injunction to the Israelites, with regard to the statues and
precepts given them, that they should "bind them for a sign upon
their hand, and have them as frontlets between their eyes," was
that they should keep them distinctly in view and carefully
attend to them. But soon after their return from Babylon they
began to interpret this injunction literally, and had
accordingly portions of the law written out and worn about their
person. These they called tephillin, i.e., "prayers." The
passages so written out on strips of parchment were these, Ex.
12:2-10; 13:11-21; Deut. 6:4-9; 11:18-21. They were then "rolled
up in a case of black calfskin, which was attached to a stiffer
piece of leather, having a thong one finger broad and one cubit
and a half long. Those worn on the forehead were written on four
strips of parchment, and put into four little cells within a
square case, which had on it the Hebrew letter called shin, the
three points of which were regarded as an emblem of God." This
case tied around the forehead in a particular way was called
"the tephillah on the head." (See PHYLACTERY T0002947.)