There are hadiths that tell us rabbit meat is haram. Therefore, this is Allah’s (swt) rule on the matter, and we have to follow Allah’s (swt) orders because they are His orders, not because in some cases we might know the some of the many reasons behind them. Of course, we believe that Allah (swt) is the All-Wise and that His orders are all based on wisdom and the good of His servants, even if we might not be aware of some of those benefits. Yet one can still find some of the reasons behind some rulings in different hadiths. For instance, regarding the impermissibility of eating rabbit meat, it has been said that the rabbit is one of the animals that have gone through metamorphosis.
All divine rules are legislated because of the wisdom and important reasons that back them; some of those reasons being mentioned in hadiths while others being left to be comprehended and discovered by man himself. Of course, there are some cases that the mind has no way in, just like there are also cases that can’t be figured out today because man still hasn’t reached the necessary level of knowledge to do so, while there are chances that in the future he will be able to do so. Therefore we can conclude that the reasons to many rulings still aren’t clear to us, yet since we know that the entity legislating these rulings is all-wise, we are to abide by all of them.
As you know, the highest form of worship is to obey Allah (swt) because He is the lord, even if the reasons behind a specific ruling might not be clear to us. This is where our servitude to Him becomes completely manifest, because even those who don’t believe in Allah (swt) will certainly act according to rulings if they are aware of its reasons and how it is completely to their benefit, so acting according to rulings that one knows the reasons for isn't a big deal, what is important is to act according to all of Allah’s (swt) rulings, regardless of the reasons behind them, or else one can dare say that there is no difference between the believer who observes rulings because of the reasons behind them and the disbelievers who do the same.
Rabbit meat is haram because of the hadiths that have reached us from the imams (as). In these hadiths it has been stated that eating rabbit meat is forbidden, and this is the reason why Islamic scholars have issued fatwas on its impermissibility. Three things can be concluded from these hadiths:
1- The rabbit is one of the animals that have undergone metamorphosis and that is why their meat is haram. The holy prophet of Islam (pbuh) has said: “The monkey, pig, dog, elephant, wolf, mouse, rabbit...are all animals that have undergone metamorphosis and eating them isn't permissible.”
There are other hadiths from the imams with the same theme. It has been said by one of the great Shia scholars, the “Shahid Thani”(the Second Martyr): “What is meant by these hadith is that the people who underwent metamorphosis and transformed, took the shape of these animals, [not that all of these animals today are actually people who have transformed into them], because people who undergo metamorphosis [as a punishment by Allah (swt)] last no longer than three days, dying afterwards.”
The fact that the abovementioned were transformed into these animals, could be a signification that these animals have an inner impurity, or else what other reason could there be for choosing these animals? There are great chances that the reason for the meat of these animals being haram is their physical and/or spiritual impurities.
2- In other hadiths, it has been said that rabbit meat is haram because as with cats, rabbits have claws, and the meat of animals of prey [animals with claws] is haram.
3- In another hadith, Imam Ridha (as) says: “Since the rabbit has blood similar to that of women [which is discharged during menstruation], its meat is haram.”
In any case, the complete reasoning behind every ruling isn't clear to us, and what has been mentioned in hadiths are only some of the reasons that might contribute to a ruling, yet since we know that Allah (swt) is the All-Wise and All-Knowing, we are sure that anything He orders us to do is to our benefit, and anything He prohibits us from doing is truly to our disadvantage and we must refrain from it.