Rashi on Leviticus 1:10/רש"י על ויקרא א׳:י׳

1ואם מן הצאן AND IF [HIS OFFERING BE] OF THE SHEEP — The ו (of אם) adds something to the former subject (i. e. shows that this is a continuation of it). Why, then, is there a break between the two paragraphs (i. e. why does the following form a separate paragraph)? In order to give Moses an interval between the one section and the next section to reflect upon what has already been said (Sifra, Vayikra Dibbura d'Nedavah, Section 5 1).

2מן הצאן, מן הכבשים, מן העזים — You have here these three words of limitating force (the three — fold “מן”; cf. Note on v. 1); they serve respectively to exclude an old, a sick and a malodorous animal from those that may be sacrificed (Sifra, Vayikra Dibbura d'Nedavah, Section 5 2; Bekhorot 41a).