"Friday nights are always my worst night of sleep because I'm up reflecting on the things I should or shouldn't have said on my live show," he said. "Last night was a particularly long night as I regret the word I used in the banter of a live moment. The word was offensive, and I regret saying it and am very sorry."
Some critics continue to call for Maher's resignation despite his apology, but HBO has not indicated it intends to cancel his show.
Maher "doesn't get a pass because we're friends," said Rev. Al Sharpton on his Sunday morning show on MSNBC.