Exodus 18:18

נבל תבל — Explain this as the Targum does: thou will certainly become weary. Its meaning expresses the idea of withering, old French flestre, just as. (Jeremiah 8:13) “and the leaf is withered (נבל)”; (Isaiah 34:4) “as withereth (כנבל) the leaf from off the vine” — the meaning being that it becomes shrivelled through the heat and through the frost, and so its strength diminishes and it becomes, as it were, weary, and falls from off the vine (מגפן)‎. גם אתה THOU ALSO — The word גם “also” was added in order to include Aaron and Hur and the seventy elders (cf. Mekhilta). כי כבד ממך FOR [THIS THING] IS TOO HEAVY FOR THEE — its weight is far more than thy strength can bear.

נָבֹ֣ל תִּבֹּ֔ל גַּם־אַתָּ֕ה גַּם־הָעָ֥ם הַזֶּ֖ה אֲשֶׁ֣ר עִמָּ֑ךְ כִּֽי־כָבֵ֤ד מִמְּךָ֙ הַדָּבָ֔ר לֹא־תוּכַ֥ל עֲשֹׂ֖הוּ לְבַדֶּֽךָ׃

Thou wilt surely wear away, both thou, and this people that is with thee: for this thing is too heavy for thee; thou art not able to perform it thyself alone.