The Duke of Edinburgh will miss a church service attended by members of the royal family, as his stay in hospital enters its fifth day.
The Queen is among those expected to attend the service at Crathie Kirk, near Balmoral, later.
But Philip, 91, continues to receive treatment for a flare-up of a bladder infection at Aberdeen Royal Infirmary.
The Duke has so far not received any visits from his relatives after doctors on Friday advised him to rest.
He was admitted to the NHS hospital on Wednesday, during his and the Queen's annual summer break at Balmoral.
Officials said at the time that he would be in the infirmary for a few days and it remains unclear when he will be discharged.
He is said to have been in regular contact with members of his family by telephone.
Buckingham Palace did not issue any updates on the Duke's condition yesterday, although he was previously said to be responding well to treatment for the recurrence of the infection he suffered in the summer.
His latest health scare comes less than three months after he spent five nights in hospital with a bladder infection following the Diamond Jubilee Pageant on the River Thames.
He had to miss some of the key celebrations for the Queen's 60-year reign after he was admitted to the King Edward VII Hospital in London the day after braving wet and windy elements on a barge for several hours.
Philip also had a successful procedure to clear a blocked coronary artery in December and was in hospital for four nights over Christmas.
Philip went to Balmoral after attending several Olympic events.
He was with the Queen during the opening ceremony and when they toured the Olympic Park.
He then saw his granddaughter Zara Phillips' Olympic equestrian debut and watched boxing a few days later.
The Duke also appeared to be in good spirits recently when he took part in events as part of Cowes Week on the Isle of Wight.
When he was in Scotland earlier this month, he supported the Queen at engagements including hosting a tea party at Balmoral.
It is not yet known whether he will attend his next official engagement - accompanying the Queen to the opening of the London 2012 Paralympic Games on August 29.