"In Al Baqara, verse 67 to 74, the prophet Mohammed said:
67. And remember Moses said to his people: "(Allah) commands that ye sacrifice a Cow." They said: "Makest thou a laughing-stock of us?" He said: "(Allah) save me from being an ignorant (fool)!"
68. They said: "Beseech on our behalf Thy Lord to make plain to us what (Cow) it is!" He said; "He says: The Cow should be neither too old nor too young, but of middling age. Now do what ye are commanded (sacrifice a cow)!"
Anybody that reads this might think, oh Moses is saying take a cow, a bull and kill it. But these verses are related with the sacred office, which is the sacrifice that we have to do.
The cow represents our physical body. We must sacrifice this cow (physical body). The sephirah Malkuth (the physical body) is always feminine (as a sephirah). Malkuth is the body of the Divine Mother. The bull Apis is in the throat. To sacrifice the cow means to enter into the mysteries of Daath and to sacrifice all the animals, the bullock, we have within, the behemoth that we have within, and to develop with the blood of the cow the sacred forces of God. That blood is the symbol of sexual transmutation, the fire that rises in the spinal medulla. This is why it is written ‘Cow,’ because the power of sex is always feminine (She)." Gnostic Instructor
Why does it say that the "Cow should be neither too old nor too young, but of middling age"?
After some reflection on this, what makes sense to me at this moment, supposing that the cow is representative of physicality, our Malkuth, is that we should sacrifice our animality with equilibrium, the approach should be in the middle of either extremes, which are attachment and aversion, although I confess that the quote itself can quite easily be mistaken for a literal command given by Allah to kill a middle aged cow... is the Quran a Kabbalistic scripture?