After Montag goes to Faber's house when he is on the run, they visit for a bit, and formulate an escape plan for Montag. Montag's entire house has just been torched, his wife has essentially betrayed him, and he has nothing left in the world. Given that, he still takes a bit of money that he had on him, and gives it to Faber. The text states that "Montag drew out a hundred dollars" to give to him, saying, "I might be dead by noon; use this." Montag, at this point, was thinking he was a dead man. The hound was chasing him, he was being taped on television, and the troops were out. So, really, what good does money do to a dead man? He gives it to Faber to help Faber in his journey out of town.
I hope that helped; good luck!