The Queen said private prayers following the death of the Duke of Edinburgh as she attended a Sunday service in Windsor Castle.
The monarch, who is head of the Church of England, is said to have a deep Christian faith and to be drawing on this in her time of grief.
The Queen is understood not to have attended the worship in the private chapel, where the duke’s coffin remains at rest, draped in his personal standard and adorned with a wreath of flowers.
The service was also not in St George’s Chapel, which is currently closed and is where Philip’s funeral will take place on Saturday.
Philip and the monarch’s second son the Duke of York has told of the depth of his mother’s feelings, saying she described the death of her husband of 73 years as “having left a huge void in her life”.
Andrew said the Queen was “incredibly stoic”, while the Countess of Wessex said the monarch was “thinking of others before herself”.
The Queen, who takes her role in the Church seriously as Supreme Governor of the Church of England, usually attends church each Sunday.
Each year, she delivers her televised Christmas message, incorporating a strong religious theme.
Following the duke’s death at the age of 99 on Friday, the Archbishop of Canterbury led tributes from faith leaders, describing Philip as an “outstanding example of Christian service”.