Numbers 33:55

Those whom you will leave over. Shall be evil to you.

As spikes in your eyes. As spikes which will gouge your eyes out. Targum [Onkelos] renders “spikes” שִׂיכַּיָא .

And thorns. The linguists construe this as denoting a barrier of thorns, which will enclose you, locking and confining you without exit or entrance.

And they will persecute you. As Targum [Onkelos] renders.

But if you will not drive out the inhabitants of the land from before you, it will be that the residue whom you have spared looking at you with an evil eye will surround you as shields (terisin) on your sides, and afflict you in the land wherein you dwell;

L’SIKIM’ IN YOUR EYES — “‘like pins’ which prick out your eyes. The [Aramaic] Targum [Onkelos] of the Hebrew word yetheidoth (pins) is sikim. ‘V’LITZNINIM.’ Translators have interpreted this [word] in the sense of [the phrase] mesuchath (hedged by) thorns encircling you so that they enclose and imprison you and you cannot go out or come in.” This is Rashi’s language.
Now it is [indeed] clear that sikim means “sharp thorns,” and is related to [the expression]: I will take away ‘mesukatho’ (the hedge thereof); I will ‘sach’ (hedge up) thy way with thorns; Hast Thou not ‘sachta’ (made a hedge) about him?; and put ‘sakin’ to thy throat — [all these phrases referring to] something sharp, made from a thorn or from iron. V’litzninim is likewise [a term for] a piercing thorn related to the expression: and taketh it even ‘mitzinim’ out of the thorns); ‘tzinim’ (thorns) and snares are in the way of the crooked, and [the word tzinim in these two verses] lacks the double letter [‘nun,’ since the full word is tzninim, as in the verse before us]. But the intention of [the expression here] ‘l’sikim’ in your eyes is: “to mislead you so that you will not see nor understand,” just as in [the expression], for the bribe ‘blindeth’ the open-eyed, and as, nor put a stumbling-block before ‘the blind,’ according to the opinion of our Rabbis. Thus the verse is saying that they [the inhabitants of the Land] will “prick out” your eyes by misleading you, because you will not perceive nor understand [the danger], and they will teach you [to do] all their abominations and to worship their gods, just as He said, They shall not dwell in thy Land, lest they make thee sin against Me, for thou wilt serve their gods. After being thorns in your eyes and misleading you to turn away from Me, they will be pricks in your sides, causing you suffering and pain, by plundering and despoiling you. And after that they shall harass you, meaning that they will fight against you and bring you under siege, and I will then send you into exile, a whole captivity, in their place. For as I thought to do unto them because of you, that is, to send all of them into exile from the Land, so that you should leave none of them any more there, but you have not hearkened to My voice, therefore so will I do unto you and I will leave not a single one of you in the Land.
In a similar way Joshua said: And they shall be a snare and a trap unto you, and scourge in your sides, and pricks in your eyes, until ye perish from off this good Land. Joshua said a snare and a trap referring to the errors into which they will lead you, as in [the expression], for thou wilt serve their gods — for they will be ‘a snare’ unto thee; and a scourge in your sides which means that they will chastise you with shotim (whips) [in Joshua 23:13, which is usually translated: as a scourge], is understood here by Ramban as coming from the noun shot (a whip). so that they may plunder, despoil and cause you great suffering; and pricks in your eyes, this refers to blinding of the perception of the heart, so as to further mislead you after their gods; until ye perish from off this good Land, similar to that which it is said, lest they, seeing with their eyes, and hearing with their ears, and understanding with their heart, return and be healed.

לשכים בעיניכם, an expression describing thorns and thistles. These pierce one’s eyes as described in Hoseah 2,8 הנני סך את דרכך בסירים, “here I am going to hedge up her roads with thorns.” We have further support for this in the Book of Joshua 23,13 והיו לכם לפח ולמוקש ולשוטט בצדיכם ולצנינים בעיניכם, “they shall become a snare and a trap for you, a scourge to your sides and thorns in your eyes.” We have a similar threat uttered by Rechavam Solomon’s son who told the people: “my father disciplined you with whips, whereas I intend to flog you with scorpions” (Kings I 12,11).

ולצנינים, anothet kind of thorns that are harmful to human beings. Menachem ben Srok understands Job 5,5 speaking of מצנים יקחהו ואל as referring to picking some harvest between the thorns and thistles, whereas I believe that the correct meaning of the word is connected to snow, i.e. צנת שלג as in Proverbs 25,13 coldness of snow. Accordingly, the meaning of the line in Job would be that “when one is forced to harvest among thorns and to slake one’s thirst by swallowing one’s own wealth, the robbers who are hungry and the naked who are thirsty will devour one’s money. [Job is expressing his frustration with the day he was born,] Our author understands the word צינים there as referring to the naked.