Final answer:
The old timer from Sulphur Creek tells the man that no one should travel alone in the Yukon when it's fifty degrees below zero.
Step-by-step explanation:
The old timer from Sulphur Creek advises the man that no one should travel alone when the temperature is fifty degrees below zero. This piece of wisdom becomes critically important as the man faces the brutal cold of the Yukon territory. Despite initially dismissing the advice, he later recognizes its value as he struggles to survive the harsh conditions and acknowledges the old timer's experience and knowledge posthumously.