Following is a sample bank account verification letter. If you are sponsoring the US visitor visa or tourist visa for someone, you should obtain this letter from your US bank.
Depending on your specific bank, the language and format of the letter may vary as per your situation. Contact and discuss with your bank for more specific information about "Bank account verification letter".
For those who have applied for a green card or are planning to apply for a green card, here is some useful information on the process.