Former Fox News host Bill O'Reilly warned the network's incoming prime-time star, Laura Ingraham, on Wednesday the Left will likely "come after you" because cable news was a "hateful arena."

"I have to warn you — for 20 years of my life, while I was on the Fox News Channel, I was attacked personally every single day. You will be, too," O'Reilly said on "The Laura Ingraham Show." "They have millions of dollars to spend to destroy me and to try to destroy Sean Hannity, who was smart enough to fight back. They're going to come after you."

O'Reilly, who was ousted from Fox News in April after it became public knowledge that he and the network settled five sexual harassment lawsuits for $13 million, also addressed earlier comments he made to Hannity on his radio program Tuesday about whether he would return to the channel.

"I have to make a decision: Do I want to come back into this hateful — and that's the word — hateful arena where the truth doesn't matter?" O'Reilly said. "Now, will I come back on conventional television? The deal has to be right. The time has to be right. So I'm taking being patient for once in my life because it's so hateful, Laura."

O'Reilly was with Fox News for more than two decades, with his show "The O'Reilly Factor" becoming one of the most watched programs on cable.

"The Ingraham Angle" — the name of her old segment on O'Reilly's show — is set to debut at 10 p.m. on Oct. 30., moving "Hannity" into the earlier time slot of 9 p.m.

O'Reilly is currently promoting his new book, Killing England: The Brutal Struggle for American Independence.