Here, Glass is referencing the biblical story of the Good Samaritan, comparing Fitzgerald and Bridger to the people who blindly walked past a robbed and wounded man and refused to give him any assistance. That's a classic 1820s burn.

See, Glass can actually empathize with his enemies. He understands that they were in imminent danger, and he knows that they needed to protect themselves first and foremost. But by stealing from him, by taking the few tools he could use to stay alive, they made an active choice to hurt him, to "kill" him, as Glass states so passionately.

Death Camas, by the way, is a plant that looks edible but is in fact poisonous. Seriously, the name should have clued you in on that one. As we can see here, however, Glass's situation has become so desperate that he's about ready to throw in the towel.