If a thief be found breaking up. This clause is to be taken separately, and is inserted by way of parenthesis; for, after having decreed the punishment, God adds in connection, "he should make full restitution; if he have nothing, then he should be sold for his theft;" and this exception as to the thief in the night is introduced parenthetically. But although the details are not expressed with sufficient distinctness, still the intention of God is by no means ambiguous, viz., that if a thief should be killed in the dark, his slayer should be unpunished; for he can then hardly be distinguished from a robber, especially when he proceeds with violence; because he cannot enter another man's house by night without either digging through a wall or breaking down a door. The Twelve Tables [1] differ slightly from this; for they permit the killing of a thief by night, and also by day if he should defend himself with a weapon. But, since God had sufficiently repressed by other laws murders and violent assaults, He is silent here respecting robbers who use the sword in their attempts at plunder. He therefore justly condemns to death those who have avenged by murder a theft in open day.

Footnotes

1 - This provision of the Twelve Tables is thus given by A. Gell. 11. ult., "Si nox furtum faxit, sim (si eum) quis occisit, jure caesus esto: si luci furtum faxit, sim aliquis endo (in) ipso furto capsit, verberator, illique, cui furtum factum escit (erit) addicitor, sed non nisi is, qui interemturus erat, quiritaret," i.e., shall have called out for assistance.

If a thief, in breaking into a dwelling in the night, was slain, the person who slew him did not incur the guilt of blood; but if the same occurred in daylight, the slayer was guilty in accordance with Exodus 21:12. The distinction may have been based on the fact that in the light of day there was a fair chance of identifying and apprehending the thief.

If a thief be found - If a thief was found breaking into a house in the night season, he might be killed; but not if the sun had risen, for then he might be known and taken, and the restitution made which is mentioned in the succeeding verse. So by the law of England it is a burglary to break and enter a house by night; and "anciently the day was accounted to begin only from sunrising, and to end immediately upon sunset: but it is now generally agreed that if there be daylight enough begun or left, either by the light of the sun or twilight, whereby the countenance of a person may reasonably be discerned, it is no burglary; but that this does not extend to moonlight, for then many midnight burglaries would go unpunished. And besides, the malignity of the offense does not so properly arise, as Mr. Justice Blackstone observes, from its being done in the dark, as at the dead of night when all the creation except beasts of prey are at rest; when sleep has disarmed the owner, and rendered his castle defenceless." - East's Pleas of the Crown, vol. ii., p. 509.

If a thief be found (b) breaking up, and be smitten that he die, [there shall] no blood [be shed] for him.
(b) Breaking a house to enter in, or undermining.

If a thief be found breaking up,.... An house, in order to steal money, jewels, household goods, &c. or breaking through any fence, hedge, or wall of any enclosure, where oxen, or sheep, or any other creatures are, in order to take them away: the Targum of Jonathan is,"if in the hole of a wall (or window of it) a thief be found;''that is, in the night, as appears from the following verse, "if the sun", &c. to which this is opposed, as Aben Ezra observes; some render it, with a digging instrument (x); and it is a Jewish canon (y), that"if anyone enter with a digging instrument: he is condemned on account of his end;''his design, which is apparent by the instrument found upon him; for, as Maimonides (z) observes,"it is well known, that if anyone enters with a digging instrument, that he intends, if the master of the house opposes him to deliver his goods out of his power, that he will kill him, and therefore it is lawful to kill him; but it does not signify whether he enters with a digging instrument, either by the way of the court, or roof;"
and be smitten that he die be knocked down with a club, by the master of the house, or any of his servants, or be run through with a sword, or be struck with any other weapon, to hinder him from entrance and carrying off any of the goods of the house, and the blow be mortal: there shall no blood be shed for him: as for a man that is murdered; for to kill a man when breaking into a house, and, by all appearance, with an intention to commit murder, if resisted, in defence of a man's self, his life and property, was not to be reckoned murder, and so not punishable with death: or, "no blood" shall be "unto him" (a); shall be imputed to him, the man that kills the thief shall not be chargeable with his blood, or suffer for shedding it; because his own life was risked, and it being at such a time, could call none to his assistance, nor easily discern the person, nor could know well where and whom he struck.
(x) "cum perfossorio", Pagninus; "cum instrumento perfosserio", Tigurine version. (y) Misn. Sanhedrin, c. 8. sect. 6. (z) Comment. in ib. (a) "non ei sanguines", Montanus, Vatablus, Drusius.

If a thief broke a house in the night, and was killed in the doing it, his blood was upon his own head. But if it were in the day - time that the thief was killed, he that killed him was accountable for it, unless it were in the necessary defence of his own life.