Who are "Chata'im"?
Rashi: They are Chot'im (sinners).
What is the meaning of "Al Tavo"?
Rashi: Do not consent to them.
R. Yonah: Separate [from bad company]. It causes man's heart to be cast off from the [good] path. So David began Tehilim "Ashrei ha'Ish Asher Lo Halach ba'Atzas Resha'im [uv'Moshav Letzim]; Ki Im b'Soras Hashem Cheftzo" (1:1-2). First one must separate from Derech Resha'im and Moshav Letzim, and afterwards meditate in Torah. Also Shlomo arranged seeking Chachmah after separating from Resha'im, and putting to heart punishment and reward, in order to fear Hashem.
Malbim: When a father wants to teach to his son conduct with Chachmah, he begins with something simple whose reason is understood, and even a youth understands it clearly. E.g. do not go with a gang of murderers to murder and steal (11). All know this, due to the severity of murder, which is against man's nature, and due to the mortal danger. The father begins to explain folly and its evil. One should not heed the enticement of sinners; it opposes the laws of Chachmah.
