Why should the Chacham not boast about his Chachmah?
Rashi: Do not say 'we are Chachamim.' You despised My words - what is Chachmah for you?! If you were astute to know Me, then you could boast about your Chachmah (verse 23).
Radak: If you have Chachamim, they should not boast about their Chachmah, for it will not help them, since they did not know Hashem and go in His ways - "Chachamim Hemah Lehara" (4:22). Similarly, Giborim should not boast about their Gevurah, for it will not help to save them from death or captivity. Ashirim should not boast about their wealth, for it will not redeem them; they and their wealth will be lost.
Radak (23, citing Rambam - Moreh ha'Nevuchim 3:54): Chachmah applies to four matters. (a) Attaining truths in order to understand Hashem - "veha'Chachmah me'Ayin Timatzei" (Iyov 28:12). (b) Knowledge of crafts - "v'Chol Chacham Lev Bachem", "v'Chol Ishah Chachmas Lev" (Shemos 35:10, 25). (c) The ultimate attributes of Midos - "u'Zkenev Yechakem" (Tehilim 105:22), "bi'Yshishim Chachmah" (Iyov 12:12). (d) Scheming - "Havah Nischachmah Lo" (Shemos 1:10) - "va'Yikach mi'Sham Ishah Chachamah" (Shmuel II, 14:2), "Chachamim Hemah Lehara" (above, 4:22). Perhaps Chachmah refers to scheming and use of intent - sometimes it is to acquire intellectual attributes or good Midos.
Malbim: They should know that there is no Chachmah, strategy or strength against Hashem. It will not help save him against Hashem's decree.
Malbim (23): Refer to 9:23:4:3.
Why does it mention Chachmah, Gevurah and wealth?
Radak, Malbim: Often a Chacham is saved via his strategy and cunning, a Gibor via his strength, and an Ashir redeems himself. These will not save them.
Radak (23, citing R. Avraham b'Ribi Chiya): If one uses Chachmah to acquire Chachmah, he is called a Chacham. When he increases his acquisition and acquires more and is Misgaber in it, he is called Gibor. One who adds onto this is called Ashir.
Radak (23, citing Rambam): Sheleimus of acquisition, physical health or good Midos is not proper to boast about. Sheleimus is knowledge of Hashem, which is the true Chachmah.
Lev Eliyahu (Shmos p.88): All of these refer to spirituality - a Chacham who learns from every person, a Gibor who conquers his nullify, and a Ashir who is happy with his portion. Even so, one may not boast about these, only that 'I have a great, absolute belief in Hashem!'
