בְּעֵט־בַּרְזֶ֥ל וְעֹפָ֑רֶת לָ֝עַ֗ד בַּצּ֥וּר יֵחָצְבֽוּן׃
Kiranya kata-kata itu dipahat dengan pena besi dan timah pada batu karang untuk selama-lamanya!
Rashi
With an iron pen they should be inscribed in the rock, and afterwards they run lead over them to give the letters a black appearance, to make them recognizable. This is the practice of those who inscribe on stone. It cannot be explained to mean a lead pen because lead is soft in comparison with stone.