Stephen Boyle, 41, of Cambridge Park, Kilburn, London, stabbed father-of-one Paul Boyle, 19 in the neck with a glass during a row.
The victim was rushed to hospital in Letterkenny following the attack but died on October 3rd, 2009.
Mr Justice Patrick McCarthy sentenced Boyle to six years in prison, backdating it to October 2009 for time already spent in custody.
During the trial the court had heard that both men had worked together previously in London and there was a question over money which led to the row.
Judge McCarthy said Boyle had a number of previous convictions of a minor nature but said he would disregard them in relation to sentencing.
He also noted that Paul Boyle’s family went through a great deal of trauma and that his parents were particularly traumatised.
The judge took account of a psychiatric report which said Boyle was of minimal risk of re-offending and that nine persons had given him the highest references.
He also noted that a defence of diminished responsibility was used during the trial but that the jury did not accept it.
Mr Vincent Heneghan BL prosecuting told the court on that date the prosecution did not accept that there was minimal risk of reoffending but that it accepted the decision of the jury.