It's All Geek to Me:
tales of the Greek Gods by Leah Samul
Eostre 90: Philemon and Baucis, or "The Story of a Happy Marriage"
The story of Philemon and Baucis is one of the most tender and lovely stories in Greek mythology. The story goes that Zeus and Hermes were walking on earth disguised as mortals. They went to various houses in Phrygia and were rudely turned away without any kindness or hospitality.
On the outskirts of one town that had been especially rude to them, they encountered an old couple living in a very poor hut. These two were Philemon and Baucis, who had been married for many years and were still happily in love with one another. They served the two disguised Gods very generously. Even though they had not much themselves, they gave the very best of what they had. Then they noticed that the wine carafe kept refilling itself, no matter how much wine they drank. They suspected the truth: that their visitors were divine.
The Gods revealed themselves and then took the couple to the top of a hill. When they turned to look at the town they used to live near, they saw that it had been turned into a lake as punishment for its cruel lack of hospitality. The poor hut of Philemon and Baucis, on the other hand, had been turned into a temple. Zeus told them he would grant them any wish. They said that they wished to be caretakers of the temple and serve the Gods all their days. And they asked that neither one outlive the other, for they could not bear to live without the love they each had felt for all these years.
Zeus granted their wish. They lived together in the temple for many more happy years. At the moment they died, they looked down and saw that they turned into trees, an Oak and a Linden, that grew side by side. (Tripp, p. 132)