C. F. Keil and Franz Delitzsch on Isaiah 40:16

Isa 40:16

By the side of this vanishing diminutiveness on the part of man as contrasted with Jehovah, everything by which man could express his adoration of the exalted One comes incomparably short of His exaltation. “And Lebanon is not a sufficiency of burning, nor its game a sufficiency of burnt-offerings;” i.e., there is not enough wood to sustain the fire, nor a sufficient supply of sacrificial animals to be slaughtered, and to ascend in fire. דּי (constr. דּי) signifies that which suffices (and then that which is plentiful); it differs therefore from τὸ δέον, what is requisite.The derivation of דּי is still more obscure than that of δεῖ, which signifies, according to Benfey (Wurzelwörterbuch, ii. 205), “there needs;” according to Sonne, “it binds, scil. ἡ ἀνάγκη.”