On the first discovery of the theft, the person wronged Judges 17:2, or the judge of the city (marginal reference), pronounced a solemn curse on the thief and on all who, knowing the offender, were unwilling to give evidence against him. The accomplice of the thief hears that curse, and yet is silent, and so falls under it, and "destroys his own soul."

Hateth his own soul - נפשו naphsho, his life, as the outraged law may at any time seize on and put him to death.
He heareth cursing - אלה alah, the execration or adjuration, (for all culprits were charged, as before God, to tell the truth), ולא יגד velo yagpid, but He will not tell It. He has no fear of God, nor reverence for an oath, because his heart is hardened through the deceitfulness of sin.

Whoso is partner with a thief,.... That robs and steals, and raises away another man's property; which to do is sinful and contrary to the law of God, and punishable by it; and so it is to join with him in the theft, or to devise, or consent unto it; or to receive the stolen goods, or to hide and conceal them; or to hide the thief, or the theft, and not declare them; see Psalm 50:18. Such an one
hateth his own soul; that is, he is not careful of it, he is not concerned for its welfare as he should be; for otherwise no man, properly speaking, hates his own flesh or body, and much less his soul; but he is negligent of the good of it, and, for the sake of the mammon of unrighteousness, runs the risk of the ruin of it; by which he shows that he loves the world more than his own soul; when the profit of the whole world is nothing to the soul of man, Matthew 16:26; see Proverbs 8:36;
he heareth cursing, and bewrayeth it not; or "does not declare it" (b); he heareth the cursing of those that have lost their goods, and yet he does not declare where they are, and who is the author of the theft, though he knows; or, being suspected of being concerned in it, or, at least, of knowing who did it, be is had before a civil magistrate, and an oath is given him, which he takes, and yet he conceals the matter: which is an aggravation of his sin, and brings ruin to his soul. So the Targum,
"an oath is determined (or brought to him) and he confesseth not.''
Some understand this of a distinct evil, of hearing cursing and swearing, and taking the name of God in vain, and blasphemy against him; yet, through fear of incurring the displeasure of men, and being reckoned a busy body, or through indifference and want of zeal for the glory of God, do not discover it, or inform of it, to a proper person, for the punishment of such; see Leviticus 5:1; and render the words (c), as "he that is partner with a thief hateth his own soul; so he that heareth cursing, and betrayeth it not."
(b) "et non indicat", Junius & Tremellius, Mercerus, Cocceius, Schultens, Michaelis. (c) So Gejerus.

The receiver is as bad as the thief.

hateth . . . soul--(Compare Proverbs 8:36).
heareth cursing-- (Leviticus 5:1), risks the punishment, rather than reveal truth.

24 He that taketh part with a thief hateth himself;
He heareth the oath and confesseth not.
Hitzig renders the first member as the pred. of the second: "he who does not bring to light such sins as require an atonement (Leviticus 5:1.), but shares the secret of them with the sinner, is not better than one who is a partner with a thief, who hateth himself." The construction of the verse, he remarks, is not understood by any interpreter. It is not, however, so cross, - for, understood as Hitzig thinks it ought to be, the author should have expressed the subject by שׁמע אלה ולא יגיד, - but is simple as the order of the words and the verbal form require it. The oath is, after Leviticus 5:1, that of the judge who adjures the partner of the thief by God to tell the truth; but he conceals it, and burdens his soul with a crime worthy of death, for from a concealer he becomes in addition a perjured man.

Bewrayeth it not - Which he is bound to do for the publick good.