Reference for Bava Kamma 209:10
אמר ליה לא צריכא כגון שנשר אחת מהן וגילח אחת מי אמרינן השתא מיהת הא ליכא שיעור או דלמא הא לאו גילוח הוא דמעיקרא הא שייר שתי שערות והשתא כי גילח לא הוי ב' שערות
that a Nazirite who performed the duty of shaving<span class="x" onmousemove="('comment',' In accordance with Num. VI, 9 and 18. ');"><sup>23</sup></span> but left two hairs unshaved performed nothing at all [of the injunction]. Raba asked: What would be the law where he [subsequently] shaved one of the two and the other fell out of its own accord? — Said R. Aha of Difti<span class="x" onmousemove="('comment',' V. supra 73a. ');"><sup>24</sup></span> to Rabina: How could it have been doubtful to Raba whether a Nazirite would have performed his duty by shaving one hair after another?<span class="x" onmousemove="('comment',' Is this not generally so in all cases of shaving? The injunction has surely been performed, since at the beginning of shaving the minimum number of hairs was not lacking. ');"><sup>25</sup></span>