Adam Clarke on Exodus 12:5

Without blemish - Having no natural imperfection, no disease, no deficiency or redundancy of parts. On this point the rabbins have trifled most egregiously, reckoning fifty blemishes that render a lamb or kid, or any animal, improper to be sacrificed: five in the ear, three in the eyelid, eight in the eye, three in the nose, six in the mouth, etc., etc.

A male of the first year - That is, any age in the first year between eight days and twelve months.

From the sheep, or from the goats - The שה seh means either; and either was equally proper if without blemish. The Hebrews however in general preferred the lamb to the kid.