Ask: how to check tenant bank balance and monthly paycheck

A new landlord here. I have a question, is it legal to ask info about tenant bank balance and their monthly income. I mean not just believe what they put on application how much money they have in their bank and how much they earn each month. Can I ask their 2 month bank statement and their pay stub?

If landlord can\'t ask those document, will bank and employer willing to providing those documents?