Metamorphoses Book 8: Philemon and Baucis
Mercury and Jove disguised themselves as mortals and roamed the earth. They were turned away by many people until they came to the poor cottage of Philemon and Baucis. They were a poor, old couple, but they offered the strangers the best of all they had not knowing that they were serving gods. Mercury and Jove revealed themselves and took the old couple up a mountain. The gods flooded the valley and purged it of the evil mortals who lived there, but they transformed Philemon and Baucis' home to a temple. The gods offered to give the couple anything they wanted, and the two asked to be temple guards and to die at the same time. When their time came, the two became two trees that shared a trunk.