India, Aug. 17 -- Britney Spears' ex-husband Sam Asghari isn't holding back when it comes to Kevin Federline's latest project. In a recent video shared by TMZ, the 31-year-old fitness mogul was asked about his thoughts on Federline's upcoming tell-all book by a photographer, and his blunt response was a serious dig at the former backup dancer.

While walking along The Abbey, a West Hollywood hotspot, Asghari savagely declared, "Well, he was a professional father," and added with a grin, "[Federline's book] would be the first book that'll tell you how to be a professional father."

Federline, who married Britney Spears in 2004, said earlier this month that his new memoir, "You Thought You Knew," will examine his well-publicized marriage to...