אֶשְׁתּוֹלְל֨וּ ׀ אַבִּ֣ירֵי לֵ֭ב נָמ֣וּ שְׁנָתָ֑ם וְלֹא־מָצְא֖וּ כָל־אַנְשֵׁי־חַ֣יִל יְדֵיהֶֽם׃
אױסן זינען זײַנען געװאָרן די שטאַרקהאַרציקע, זײ זײַנען אײַנגעשלאָפֿן זײער שלאָף;און אַלע קריגסלײַט האָבן ניט געפֿונען זײערע הענט.
Rashi
I will go mad Heb. שׁוֹלָל, becoming mad like a mentally deranged person, with bewilderment. Cf. (Ps. 76:6) “The stout-hearted have become mad (אֱשְׁתּוֹלְלוּ)”; (Isa. 59:15) “And he who turns away from evil is considered mad (מִשְׁתּוֹלֵל).” The ‘tav’ comes into the word to serve in the reflexive present and past. This is the normal pattern of a word whose first radical letter is ‘shin’ or ‘sammech’ when a ‘tav’ is added in the reflexive, either present or past, as in מִשְׁתּוֹלֵל. I say that it is an expression of error, as in (II Kings 4:28) “Do not mislead (תַשְׁלֶה) me”; (II Sam. 6:7) “For his error (הַשַּׁל) ;” (Dan. 3: 29) “who speaks anything amiss (שָׁלוּ).”
Malbim
Recognizing this to be so, Maimonides in his Guide to the Perplexed, and likewise all the upright in heart (Psalms 94:15), sought to identify each debater with a particular philosophical standpoint. However, when they tried to explain and interpret the book's actual text accordingly, none of these worthies succeeded (Psalms 76:6). For at first sight, there appears to be a great confusion which destroys (Exodus 8:20) any systematic pattern the book may have, from its beginning to end. Not only is order not maintained, as it should be in a scholarly debate, but neither are questions asked or answered to the. The topics should follow on from one another by way of ordered and systematic statements, in a logical and rational progression. Answers should relate to the questions previously asked and subsequent questions should be a rebuttal of the replies previously given. But everything is confused and disconnected.
Ibn Ezra
משתולל According to some it means "mad;" comp. שולל "mad"13A. V., "stripped." (Mic. 1:8); אשתללו "they are mad" (Ps. 76::6); perhaps all these words are serived from שלל "to deprive of property;"14The meaning of משתולל accordingly is "maketh himself a prey (A. V.). משתולל is the participle Hitpael of שלל.
Rashi
madness Heb. שולל. It is a noun, ‘madness.’ He leads them away with madness when He wishes to confuse and destroy their wisdom, as in (Isa. 59: 15), “and he who turns away from evil is considered mad (משתולל)”; (Ps. 76:6), “The stouthearted became mad אשתוללוּ.” The “tav” in משתולל and in אשתוללוּ [is inserted because] so is the structure of the Hebrew language: in a word that has a radical “shin” or “sammech,” and which is used in passive or reflexive conjugation, a “tav” is placed after the first radical, like (Ecc. 8:10), “and they will be forgotten (וישתכחו) in the city”; (Micah 6: 16), “For the statutes of Omri are kept (וישתמר)”; (Exod. 9:17), “You still exalt yourself very high (מסתולל) above My people”; (Ecc. 12:5), “and the grasshopper shall drag himself along (ויסתבל).”