It appears that the words YHWH (Yahweh) and YRŠLM (Jerusalem) feature in the inscriptions, which Joseph Naveh dated to the late 6th century BCE.
[1][2] Naveh read it as יהוה אלהי כל הארץ הרי יהד לו לאלהי ירשלם yhwh ʾlhy kl hʾrṣ hry yhd lw lʾlhy yršlm which he translated as "Yahweh (is) the God of the whole earth; the mountains of Judah belong to him, to the God of Jerusalem".
[3][4] Frank Moore Cross disagreed with many of Naveh's readings of the letters, instead interpreting the inscription as a poetic rubric in the first person: "I am Yahweh thy God: I will accept the cities of Judah, and will redeem Jerusalem".
[5] Cross speculated that it was "the citation of a lost prophecy", perhaps written by a refugee fleeing the 587 BCE destruction of Jerusalem.
[6] Other scholars, including Lemaire and Puech, have proposed additional readings.