Deuteronomy 18:4

ראשית דגנך THE FIRST-FRUIT [ALSO] OF THY CORN … [THOU SHALT GIVE HIM] — This refers to the heave-offering. Scripture, however, does not state any minimum quantity, but our Rabbis fixed a quantity for it from a sixtieth to a fortieth: a benevolent eye (a generous person) gives one fortieth of the crop, a niggard at least one sixtieth, a person of average generosity one fiftieth. They found a support in Scripture that one should not give less than one sixtieth, because it is said, (Ezekiel 45:13) “[This is the heave-offering which ye shall offer:] the sixth part of an ephah of an homer of wheat”. Now the sixth part of an ephah is a half Seah; if therefore you give half a Seah as Terumah from a Kor (which is another term for a Homer), that is a sixtieth part, for a Kor is thirty Seahs (Talmud Yerushalmi Terumot 4:3). וראשית גז צאנך AND THE FIRST OF THE FLEECE OF THY FLOCK [SHALT THOU GIVE HIM] — i.e. each year when you sheer your sheep (not when you shear a particular animal for the first time) give the first of it (the wool) to the priest. Scripture mentions no minimum quantity for it, but our Rabbis assigned a quantity for it, viz., one sixtieth part. And how many sheep must there be in the flock that they should come under the law of ראשית הגז (of “giving the first shearing as a gift to the priest”)? At least five sheep, as it is said, (I Samuel 25:18) “[Then Abigail made haste and … took] five sheep ready dressed (עשויות). Rabbi Akiba says: we may derive it from our text itself, as follows: ראשית גז suggests two, צאנך also two, together four, תתן לו one, — altogether five (Chullin 137a; Sifrei Devarim 166:9).

רֵאשִׁ֨ית דְּגָֽנְךָ֜ תִּירֹשְׁךָ֣ וְיִצְהָרֶ֗ךָ וְרֵאשִׁ֛ית גֵּ֥ז צֹאנְךָ֖ תִּתֶּן־לֽוֹ׃

The firstfruit also of thy corn, of thy wine, and of thy oil, and the first of the fleece of thy sheep, shalt thou give him.