Certificate of Regularity - Buyer's attorney is requesting one

Howdy,

I picked up a property at a NJ Sheriff Sale, renovated, and now selling. 

I had a title search done. I did not get title insurance.  

I am selling the property and the buyer's attorney is requesting a 'Certificate of Regularity'.

This seems like a document that certifies that the foreclosure process was followed correctly.

Should I attempt to contact the law firm that the bank used for the foreclosure??

Is this a normal thing?

Thanks for any help!