וְלֹא־יָבֹ֧אוּ לִרְא֛וֹת כְּבַלַּ֥ע אֶת־הַקֹּ֖דֶשׁ וָמֵֽתוּ׃ (פ)
Targum Jonathan on Numbers
But they shall not go in to gaze, when the priests go in to cover the vessels of the sanctuary, that they die not by the flaming fire.
Targum Jerusalem
And the Levites shall not go in to gaze when the priests cover the vessels of the holy house, lest they die.