The executive in question is British born of Indian heritage and I don't disagree with his assessment of Mohammed's behaviour. But: either he was completely barking mad to send such a text or he has been set up by someone with a grudge - maybe the Muslim colleague himself?  From the Daily Mail   

A high-flying British executive accused of calling the Prophet Mohammad a 'complete paedophile' is facing up to three years in a Dubai jail. Deep Marwaha allegedly texted a Muslim colleague with a volley of abuse after he performed a holy ritual while the pair were working in Saudi Arabia.

The 35-year-old, a manager at UK-based conference organising firm Informa, was said to have texted fellow Brit Khalid Shafique with the words: 'F*** you, f*** your Islam and f*** your prophet. Your Prophet Mohammad is a complete paedophile. Now show what you can do. I know lots of sheikhs.'

Fellow Informa colleague Mr Shafique, 34, complained to police that Marwaha was angry when he went to perform Umrah, a form of pilgrimage in Mecca, when their business meetings were over for the day. He resigned from the company and claimed he received the insulting text message two days later at 1.15am.

But Marwaha, who went to £15,000-a-year Latymer Upper School in west London before studying at Middlesex University, denied sending the abuse and said he was sleeping when the messages were sent. His lawyer persuaded judge Zakariah Abdulaziz to postpone his trial so he could conduct a technical experiment to show how text messages could have been sent from the defendant's phone remotely by someone else.

Both Marwaha and Mr Shafique, who are British but live in Dubai, are frequent visitors to Saudi Arabia.

Marwaha, whose family is of Indian origin but was born in London, has been heavily involved in £17 billion Saudi government plans to overhaul the infrastructure of Mecca, the holy city for Muslims, and was a key organiser of a Future Makkah (Mecca) conference in Jeddah last year

His brother Rohan was recruited in 2002 as managing director of Cityscape Dubai, staged by Informa and one of the world's biggest property sales exhibitions, and he followed him to the Middle East four years later to help manage branch offices around the region.  Marwaha has been manager of Informa's Saudi Arabia office for the past three years.

Mr Shafique told police the pair flew to Saudi Arabia for business meetings on March 11 but while Marwaha stayed in their hotel when their work was finished, he made his way to the pilgrimage site. (How big is the exclusion zone to non-Musims around Mecca? This makes it sound like Shafique just popped along for an hour. I think he must have had some distance to travel) Marwaha allegedly became agitated with him at the airport as they left, telling him prayer and pilgrimage were not allowed under company rules.

Mr Shafique said: 'He asked me why I had performed Umrah. I asked him why I should not have gone [and that] I went in my free time to pray. He said prayers and Umrah were not part of our company's policy. I resigned on March 15 and on March 17 I received offensive messages from his mobile phone.'

The defendant, who is charged with insulting Islam denied sending any texts . . . The trial was adjourned until September.