Ascend Over Flesh is activated just after the quest "Two Roads Diverged".
This is also the only appearance of Sabit in the game.
Prior to "Ascend Over Flesh"/During "Two Roads Diverged"
Sabit was a forest ranger within the Countryside, being described by Jasir as someone who always preferred living along with nature and always being of a courageous and brave manner. Jasir states that Sabit was so brave and fearless that he used to venture out at night with no regular protection i.e. UV flashlights and UV flares, even if there was a heavy presence of Volatiles within the areas Sabit travelled through.
Sabit lived in a hut towards the south of the Countryside, located away from the roads in the middle of an island.
Sabit also only travelled around the Countryside on foot, as opposed to how Crane would usually travel via use of his personal buggy, again showing how Sabit was "close to nature". This probably made travelling at night easier for him as Volatiles have a wider detection radius regarding those travelling in vehicles.
It is also discovered upon arriving at Sabit's hut that his residence is only fortified with a boarded-up door and boarded up windows, instead of being protected by concrete walls, metal fencing/barricades and making use of UV lights which are present on every safe zone to prevent the Volatiles entering.
During "Ascend Over Flesh"
Once entering the hut, it is found that there is a hole where the central part of the hut's floor should be. After climbing down into the hole, strange noises can be heard as Crane discovers that there is an entire cave underneath Sabit's hut.
The quest item is also located down here, along with some other items. Venturing further will result in the onscreen message "Entering Hive" along with a Volatile Activity message stating "Heavy Volatile Activity" (just like how it will show if the player was to enter a Volatile Nest). Crane will inform Jasir that there's no sign of Sabit, before exclaiming that there's a Volatile Nest underneath Sabit's hut. Jasir will warn Crane to not go down there, as "those hives are certain death".
Crane then follows along the cave/entrance to the nest, hearing a demonic voice saying "Please! Just let me die!" Crane then rapples down a rope from the cave's ceiling, leading down to the main cavern of the Hive itself. The Hive is surprisingly empty, regardless of whatever time of day this quest is done as well as despite the Hive Status stating "Heavy Volatile Activity".
After rappelling down the rope, the only occupant of the Hive is Sabit, who is already in the transformation process into a Volatile. He pleads with Crane to kill him and "have mercy". Crane mercy-kills Sabit, stating "No need for Jasir to hear about this".
Crane then leaves the Hive and then the hut, returning to Jasir with the quest items. Sabit and his hut see no other feature or mention in the Following afterwards.