Shemot 28:36

ציץ — This was a kind of golden Plate, two fingers in breadth, going round the forehead from ear to ear (Shabbat 63b).

וְעָשִׂ֥יתָ צִּ֖יץ זָהָ֣ב טָה֑וֹר וּפִתַּחְתָּ֤ עָלָיו֙ פִּתּוּחֵ֣י חֹתָ֔ם קֹ֖דֶשׁ לַֽיהֹוָֽה׃

And thou shalt make a plate of pure gold, and engrave upon it, like the engravings of a signet, Holiness to the Lord.