The trial of 35 Sunni Muslims in a special court in Pakistan, which was due to begin on Wednesday, has been postponed until 7 May.
The defendants have been charged with the murder of five members of the Ahmadi sect.
The date for the hearing was changed after the judge failed to arrive on Wednesday.
The crime took place in November last year, while the Ahmadis were praying inside their place of worship.
The Ahmadi sect, which was legally excommunicated in Pakistan more than a quarter of a century ago, blames the Sunni community for sectarian attacks, but Sunni groups deny this.
Ahmadi facts
Not recognised as a legal Islamic sect in Pakistan
Barred from claiming Islam as their religion
Not allowed to pray in public
Say they are constantly attacked and discriminated by hardline Sunnis
The murders of the five Ahmadis took place in a remote village in the district of Sargodha in the province of Punjab.
Among the dead were two teenage boys, who had been in the Ahmadi mosque at the time of the attack.
Thirty-five Sunni Muslims are charged with carrying out the attack.
Their trial will take place at an anti-terrorism court, where the prosecution will bring in its witnesses.
However, the court will also hear a petition from the group of Sunnis who, in turn, say the attack was triggered when one of their local leaders was allegedly abducted and beaten by some Ahmadis.
Excommunicated
More than 25 years ago, Pakistan's parliament excommunicated the Ahmadi community from the legally recognised group of Islamic sects based on a key theological difference.
Some 10 years later, this was followed by further legislation, which barred the community from claiming Islam as its religion or from offering prayers in public.
Since then, the Ahmadi community have frequently alleged that sectarian violence has been directed at them by hardline Sunni groups, and they have complained of discrimination in public and social life.
A recent report released by the Ahmadi community alleged that members of their sect had suffered numerous physical assaults in the last year, including two large-scale incidents in which 10 Ahmadis were killed in the districts of Sialkot and Sargodha in Punjab within a span of two weeks.