Judge William E. Stewart Jr. said flatly that it was the toughest decision he has had to make during his seven years on the D.C. Superior Court bench.

It is true, he told a hushed courtroom yesterday, that a 12-member jury had rejected Beverly Ann Ion-Tamas' claim that she shot her husband in self-defense. And it is true, the judge continued, that the jurors had decided she had acted maliciously when she killed him.

"There are crimes . . . that are not to be tolerated by a civilized community." Stewart said, adding that the severity of criminal sentences and the words of a judge when he imposes sentence are important reminders to the public that certain acts are not permissible.

But murder within a family, Stewart said, is "totally seperate and apart and has to be considered for all the circumstances."

Punishment and deterrence must be considered, but Stewart said, "There is nothing that the prison system can offer (Mrs. Ibn-Tamas) in the way of rehabilitation."

"We all know," he said, "there is no longer punishment that can be inflicted . . . than the punishment inflicted by one's own conscience."

And so, Stewart sentenced the 34-year-old Washington woman, whose husband was portryed to the court as a brilliant neurosurgeon who could be both loving and abusive to his wife, to not more than one and no more than five years in prison for her crime. Mr. Ibn-Tames was convicted of second-degree murder while armed.

A registered nurse, pregnant with the couple's second child when she killed her husband, Mrs. Ibn-Tamas has already served seven months in jail in connection with the offense. Stewart yesterday gave her credit for that prison time and in five months she will be eligible for parole.

The dramatic hearing yesterday, marked by Stewart's comments concerning the delimma he confronted with a mixture of law and compassion, brought to a formal close Mrs. Ibn-Tamas' second emotion-charged trial.

She was found guilty of the charge in October, but another Superior Court Judge threw out the conviction after he ruled her attorneys showed they were more interested in their fee than in her defense.

At the second trial last month, Mrs. Ibn-Tamas was represented free by William E. McDaniels and Ellen S. Huvelle, attorneys with the large Washington law firm of Williams and Connelly.

McDaniels told Stewart yesterday that Mrs. Ibm-Tamas was no threat to the safety of other members of the communitty. Her actionson the morning of Feb. 23, 1976, were those of a woman feced with "intolerable domestic circumstances."

Assistant U.S. Attorney Hamilton P. Fox 111 countered that nothing is right about a woman taking revenge, even when abuse has been "heaped upon her."

"This kind of behaviour should not be encouraged," Fox said.