According to the post, the customer left a $1,000 tip for a $63.31 order and wrote "stay well" on her receipt.
"She said she was just happy that we are still open," Fentons wrote on Facebook. "Amazing. And WOW. And Thank You! What a Year!"
"We are filled with Gratitude for ALL who have been able to stay in there with us this past year via take-out orders, curbside pickup, deliveries, gift card orders, caramel & chocolate sauce orders shipped to friends, Cake Orders, sweet notes of encouragement to us, and more," Fentons wrote.
"We are very fortunate to have made it through this past year and Thank You All for your Love and Support!!" the parlor added.
According to CBS San Francisco, Fentons has been open since 1894 and has operated out of its current location for the last 60 years.