English: Cleaving is only by hand — and so it says, “and he rent it as one rends a kid.”
In the sugya: Shisa is defined as a manual act. The parallel language of tearing a kid (which is done by hand) confirms that the bird is split by the kohen’s hands, not with a blade.
Type of Learning
Diyuk that shisa is manual — by hand, not with a knife.
What Is Learned
The bird is split by hand, not with a knife. The verse’s term for cleaving, supported by the parallel of rending a kid, requires a manual act rather than the use of a cutting instrument.