Latest Facebook Messenger 139 user agents:

User Agent Platform Device
Mozilla/5.0 (Linux; U; Android 4.3; pt-pt; HUAWEI G6-L11 Build/HuaweiG6-L11C02B120) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30 [FB_IAB/MESSENGER;FBAV/139.0.0.17.85;] Android 4 Ascend G6
Mozilla/5.0 (Linux; Android 6.0.1; VFD 600 Build/MMB29M; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/62.0.3202.73 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/139.0.0.17.85;] Android 6 Smart Prime 7
Mozilla/5.0 (Linux; Android 6.0.1; STARADDICT 6 Build/MMB29M; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/61.0.3163.98 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/139.0.0.17.85;] Android 6 StarAddict 6
Mozilla/5.0 (Linux; Android 6.0.1; SM-A500FU Build/MMB29M; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/62.0.3202.84 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/139.0.0.17.85;] Android 6 Galaxy A5 Duos
Mozilla/5.0 (Linux; Android 5.1; VF-795 Build/LMY47D; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/58.0.3029.83 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/139.0.0.17.85;] Android 5 Smart Speed 6
Mozilla/5.0 (Linux; Android 5.1; NOS NOVU II Build/LMY47I; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/62.0.3202.84 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/139.0.0.17.85;] Android 5 Novu II
Mozilla/5.0 (Linux; Android 5.1.1; SM-J500FN Build/LMY48B; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/61.0.3163.98 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/139.0.0.17.85;] Android 5 Galaxy J5 (2015)
Mozilla/5.0 (Linux; Android 5.1.1; SM-J500FN Build/LMY48B; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/59.0.3071.125 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/139.0.0.17.85;] Android 5 Galaxy J5 (2015)
Mozilla/5.0 (Linux; Android 5.1.1; SM-J320F Build/LMY47V; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/61.0.3163.98 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/139.0.0.17.85;] Android 5 Galaxy J3 (2016)
Mozilla/5.0 (Linux; Android 5.0; E2303 Build/26.1.A.2.167; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/61.0.3163.98 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/139.0.0.17.85;] Android 5 Xperia M4 Aqua
Mozilla/5.0 (Linux; Android 4.4.2; CHC-U01 Build/HuaweiCHC-U01) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/30.0.0.0 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/139.0.0.17.85;] Android 4 G Play Mini