Mubarak was shown working from his hotel in Germany
Government-run mosques across Egypt offered prayers for President Hosni Mubarak's recovery on Friday.
Mr Mubarak, who is 81, is still in Germany recuperating from surgery he underwent nearly two weeks ago.
Official media in Egypt report that his recovery is going well, but no date has been set yet for his discharge.
The health of Mr Mubarak is a taboo topic in Egypt, and a cause of political and economic uncertainty because he has no obvious successor.
A senior official from the ministry of religious endowments told al-Masry al-Youm newspaper that praying for the head of state was the religious duty of all Muslims.
On Friday, Egyptian television broadcast new pictures showing Mr Mubarak sitting at a table and going over paperwork with his chief of staff Zakaria Azmi at the Heidelberg University Hospital.
Stock market boost
The Egyptian stock market was boosted by the broadcast. Concern that the president's condition was more serious than the government was letting on had driven market levels down.
Mr Mubarak had his gall bladder and a growth on the small intestine removed on 6 March.
The veteran leader has been in power for 29 years. His fifth six-year term ends in 2011.
In 2004, he underwent back surgery - also in Germany - and handed over power temporarily to former Prime Minister Atef Obeid.
And in 2003, he collapsed during a televised speech in parliament, apparently from a bout of flu.