Saigon is a very open country. It welcomes all religions and beliefs so expats and foreigners can freely practice their faith without inhibitions. There are a number of mosques where Muslims can go to practice their faith. The most well known is Jamia Al Musulman Mosque, but you can also check out other options below:
Jamia Al Musulman Mosque: 66 Dong Du, D1
Jum ah Nancy/Masjid Jamiul Islamiyah: 459 Tran Hung Dao, D1; +84 28 3920 3325
Al Rahim Mosque: 45 Nam Ky Khoi Nghia, D1
Masjid Mosque: 317/27 To 18, Hem 285 Cach Mang Thang Tam, D10