As part of "Two Roads Diverged", Crane will have entered Sabit's house and discovered the floor has caved in, leading to a cave. Despite the game's warnings that there is heavy volatile activity within the hive, it remains safe (even during the day) to explore during this mission.
"It burns... Mercy..."
Sabit
Following the path and using the zipline downwards, you will soon find the source of the noise: a half-formed volatile writhing about, revealed to be Sabit. He can be heard crying out in agony, his voice distorted by the mutations, to which Crane expresses fear and disgust.
After mercifully killing Sabit, the player must then exit the cave through the underwater tunnels, which can be found nearby.