Commento su Numeri 6:9

בפתע — This refers to a Nazarite who defiles himself thus by accident.

וטמא ראש נורו, and he defile his consecrated head, etc. Both the letter ו in the word וטמא as well as the word ראש appear superfluous in our verse. The meaning may be that even if the ritual impurity contracted by the Nazirite was unintentional, not only does his body become ritually impure but also the hair on his head, as the Torah refers to his hair as "the crown of G'd which is on his head."

בפתע פתאם, “suddenly, unexpectedly;” the word means the same as אדמת עפר in Daniel 12,2. where he describes sudden resurrection of the dead. The Nazir, as opposed to most other instances when a sin-offering has to be brought, brings such an offering regardless of whether he defiled himself knowingly or unwittingly. This is what our sages said in Keritut 9: four people have to bring an offering both if they committed an intentional wrong and if they committed the same wrong unintentionally. They are: 1) the Nazir, 2) the person who swore an untrue oath concerning what happened to an item entrusted to his care. 3) Swearing a false oath through testifying to an event which did not take place as described. 4) A person who engaged in sex with a partially freed slave-woman. He receives 39 lashes and brings an offering.
Concerning the impurity contracted by that Nazir the Torah wrote both the word פתע and the word פתאם. The reason is that the word פתע speaks of an inadvertently contracted impurity. The word פתאם speaks of an intentional defilement by the Nazir, something our sages derive from Proverbs 22,3 where Solomon writes ופתיים עברו ונענשו, “the fools kept going and were punished.” This indicates that both the willful and the merely foolish have to endure the punishment. As far as the other candidates for such offerings are concerned, the Torah added the words ונעלם ממנו, “it (the commission of a sin) was concealed from him,” in each example. The only exception to this rule is Leviticus 5,24. This proves that in the situation described in that passage it makes no difference if the error was committed knowingly or not. In both situations the guilty party has to restore the object, add 25% as punitive damages, and offer a guilt offering to expiate for what he had done. The laws pertaining to the other three examples we mentioned are all based on the law applying to the person who swore an oath denying he had trespassed against an article entrusted to him. The method used to do this is called gezeirah shavah, similar sounding words being used by the Torah in subjects which are not conceptually related to one another. It is presumed that the relevant expression was not needed to give us the plain meaning of the verse in question. The word in question is תחטא. In connection with the man who had sexual intercourse with the semi-free slave, the Torah adds the words ונסלח לו, “he will be pardoned,” again making the deed subject to an offering regardless of the awareness of the sinner at the time. Seeing that it is the function of the guilt-offering to obtain forgiveness for the sinner, it seems reasonable to see in the unnecessary mention of this result a reference to the fact that even a deliberate perjury can be wiped out through this offering.