Thank you for reaching out to the community and I'm very sorry for the longer waiting time.
The important question to ask here is - has your friend spoken about his intended leave with the Ausländerbehörde (Foreigners Office) before he left Germany?
Please have a look at Thorgen's answer from the following thread:
For how long can a refugee stay outside of Europe (maximum)?
As he explains:
"You can stay in a visa-free country for a maximum of 90 days within a period of 6 months. If you entered a country with a visa, the maximum length of your stay is determined by the terms and conditions of your visa.
If you plan staying abroad for more than six months I'd highly recommend to get in touch with with Ausländerbehörde first. Maybe they can make an exception. Otherwise your Aufenthaltsgestattung expires after six months."
You can also find a short explanation of "Asylum and Travel Restrictions in Germany" by Infomigrants here: http://www.infomigrants.net/en/post/12444/asylum-and-travel-restrictions-in-germany-what-you-need-to-know
I hope I was able to help. Please feel free to reach out to the community again if you need any further assistance!
All the best,