Let them curse it that curse the day. Very different explanations are given of this passage. Some suppose it to mean, "Let those desperate men curse it who are in the habit of cursing their day," like Job himself (Job 3:1) and Jeremiah (Jeremiah 20:14).
Others suggest a reference to such as claimed power to curse days, and to divide them into the lucky and the unlucky. In this case Job would mean, "Let the sorcerers who curse days curse especially this day," and would thus seem, if not to sanction the practice, at any rate to express a certain amount of belief in the sorcerers' power.
The second clause has also a double interpretation, which adapts it to either of these two suggested meanings (vide infra). Who are ready to raise up their mourning. This is an impossible rendering. Translate (with the Revised Version), who are ready to rouse up leviathan.
"Rousing leviathan" may be understood in two ways. It may be regarded as spoken in the literal sense of those who are rash enough and desperate enough to stir up the fury of the crocodile (see the comment on Job 41:1), or in a metaphorical sense of such as stir up to action by their sorceries the great power of evil, symbolized in Oriental mythologies by a huge serpent, or dragon, or crocodile.
On the whole, the second and deeper sense seems preferable; and we may conceive of Job as believing in the power of sorcery, and wishing it used against the night which he so much dislikes.