Future Says Ciara's Lawsuit Is a Joke ... She's Making Money Off Bad Mouthing Me

Ciara's throwing $15 million rocks from inside a giant glass house ... which is why Future thinks she doesn't have a chance in hell of winning a dime off him. 

Sources close to Future tell TMZ, the rapper thinks it's absurd his baby mama filed the slander suit, since she's talked plenty of trash on him. We're told he believes Exhibit A is her 2015 platinum selling hit, "I Bet." 

With lyrics like ... "You know that it hurts your pride but you thought the grass was greener on the other side.

Singer Ciara Sues Baby Daddy Future For $15 MILLION For Calling Her A Bad Mother

Ciara and Future's war just got way more heated -- she's suing him for allegedly blasting her mothering skills and attacking her relationship with Russell Wilson ... all to publicize his music.

In the suit ... obtained by TMZ, Ciara calls out Future for a radio interview in which he discussed a now infamous photo of Wilson pushing Ciara and Future's son in his stroller. Future said, "She probably set him [Russell] up. You letting them catch that photo. Leave my son out of all the publicity stunts."