As extremely cold temperatures continue to plague the US, one good Samaritan took it upon himself to provide a homeless man in Chicago with the proper footwear - from his own feet.

Proving that there are still good people in the world, the act of kindness was captured by fellow passenger Jessica Bell, who posted what she witnessed on Facebook.

The post, which has since been shared more than 17,000 times, has received an outpouring of praise for the unknown man’s generosity.

According to her Facebook post, Bell was taking the train home on Friday when she noticed a homeless man sitting across from her.

Bell wrote that the man was wearing tattered shoes with the heels folded down, and “I don’t know how many pairs of socks he’s wearing in an attempt to keep his feet warm but there is blood seeping through.”

On the same train was another man, “younger, carrying a satchel and a suitcase, also minding his own business.”

The second man, who Bell described as wearing big black snow boots, “they look new; they look expensive; they’re built for a Chicago winter,” then does an incredible thing.

In what Bell describes as a “blink and you’ll miss it fashion” the younger man pulls off his own boots and “passes them to the old man. He opens his suitcase and gives him a pair of socks as well.”

According to Bell, the young man then proceeded to put on a different pair of shoes - not as nice as the ones he has given away, tells the old man to try and clean his feet and change into the new socks as soon as he can, and then disembarks the train on 87th.

Concluding her post, Bell wrote: “I love my sh*t-hole city. I love that in a time and place where hate and apathy are rampant, quiet compassion appears without warning.”

The story has received thousands of comments, with many people describing how moving they found the act of compassion.

One woman wrote: “God bless them both and keep them warm”

Another said: “We can all learn from that young man.”

Others are thanking Bell for sharing the story - as a reminder that there are still good people in the world.