Abu Abdullah (as) said: O Mufazzal! It is an obligation, which Allah (swt) has obligated upon our (as) shias, in His (swt) Book when He (swt) said: You will never attain to righteousness until you spend from what you love [3:92].
So we (as) are the righteousness and the piety, and the way of Guidance, and the door of piety. And do not veil (yourselves) from our (as) supplications from Allah (swt); confine (yourselves) to what is permissible and (stay away from) what is prohibited. Ask!. But beware of asking anyone from the Fuqaha about what does not concern you, and about what Allah (swt) has veiled from you.
[Source: Tafseer Al Ayyashi 85/184:1]
The Fuqaha are not mujtahids. They are the narrators of hadith. They are well versed with hadith. Those who present hadith as the answer to all religious questions. Not the ones who produce a fatwa that is based on illegal sources.