Hullin 136: Fleecing the Impure

3 universally accepted lenient halakhot at that time: 1. The first shearing of the wool applied only in the land of Israel (a reduction of obligation, as compared to the mishnah). 2. The words of Torah are not susceptible to ritual impurity. 3. The complicated requirements to violate the law of "mixing kinds," wherein 3 separate elements had to be planted together. Also, note that the "first fleece" had other stringencies that were part of it (eg - whether the treyfot of these sheep would be obligated in the first fleece). And how that is learned from the verses, including a "gezerah shavah" (but which one?).