I am a Muslim who practices fasting in Ramadan. Me and my Muslim friends who are professionals we always talk about how lovely it is when we invite people/colleagues on Iftar especially if they were people who are not familiar with Ramadan; so that gives us chances to talk about it, its reasons and tradition.
Iftar is when sun sets and we break our fast -> eat dinner. It is very unlikely to practice religious activities on Iftar time, because Iftar is for EATING, when Muslims had all day and still have all night for religious activities if a Muslim wanted to. And It is highly likely to invite friends and family into Iftar. You would realize that Ramadan is all about getting together. Also, you would realize that 5 to 15 days (out of the 30) Muslims will manage to have Iftar somewhere outside: Restaurants reservations, friends' invitations, family invitations.. etc, and other 5 to 10 days Muslims will invite friends and family for iftar.
I would ask if colleagues are interested to join an Iftar Reservation with him (it is always at night). If they are interested, reserve an Iftar for everyone and invite him.
If none of the team can/want to join his night iftar, then reserve a Ramadan Iftar at his favorite restaurant and give it to him (gift card?) and do a small get-together on lunch break (in that same day) for the team to say good bye to him.
I believe he would love it if you guys joined him for an iftar, but this is just my opinion.