Deuteronomy 15:19

All the firstling males that come of thy herd, or of thy
flock, thou shalt sanctify unto the Lord thy God
According to the law in ( Exodus 13:2 Exodus 13:12 Exodus 13:13 ) . (See Gill on Exodus 13:2); (See Gill on Exodus 13:12); (See Gill on Exodus 13:13);

thou shalt do no work with the firstling of thy bullock:
as to plough or tread out the corn with it, which were done with other heifers:

nor shear the firstling of thy sheep;
nor was the wool shorn of it to be made use of; one of the Jewish canons runs thus,

``if any man weave an hand's breadth of the wool of a firstling into cloth, the cloth is to be burnt ^F12.''