"Your honor, in the name of almighty Allah, I am a Muslim. I believe that my religion requires me to wear a beard," Hasan told the presiding judge, Col. Gregory Gross, CNN reported.
Gross said Hasan was still in contempt of court for not shaving his beard in line with Army regulations, and asked him why he not shaved.
Hasan's response was the first statement he has made in court.
"I am not trying to disrespect your authority as a military a judge. And I am not trying to disrupt the proceedings or the decorum of the court. When I stand before God I am individually responsible for my actions," Hasan said.
Gross again found Hasan in contempt and sent him to a trailer where Hasan watched the rest of the hearing on closed circuit television. Gross has threatened to have Hasan forcibly shaved to ensure "a military trial proceeds without a distracting and disruptive sideshow," CNN said.
If not forced to shave, prosecutors said, Hasan "injects potential error" into the trial and he will "further inflame the [military court] panel to his own detriment."
Hasan's court-martial -- on charges of killing 13 people and wounding 32 others when he opened fire at Fort Hood's processing center in November 2009 -- has been delayed a week due to the facial-hair issue, which began in June when Hasan first appeared in court with a beard.
A hearing was scheduled for Sept. 6 to examine whether Hasan's religion can keep him from being forcibly shaved.