וזאת תורת הנזיר ביום מלאת ימי נזרו... והקריב את קרבנו לד'... וכבשה אחת בת שנתה תמימה לחטאת
The nazir completes the time limit of his own abstinence and brings varied korbanos. One of the nazir’s korbanos is a chatas, sin-offering. The Ramban explains that the nazir is considered a “sinner” solely because he ended his vow of abstinence. Having achieved such a lofty spiritual perch he should have remained there, ensconced in spirituality. Why did he leave? Why did he return to a mundane life? Once a person takes a giant step forward/upward, he indicates that he is special. Why not stay in that position? Returning is an indication of weakness, warranting a sin-offering. Ish or isha…