Mishkat al-Masabih 533, 534

Abū Saʿīd al-Khudrī said: ‘Two men set out on a journey. When prayer time came, they had no water, so they performed dry ablution with clean earth and prayed. They then found water while the time remained. One repeated the ablution and prayer, but the other did not. Later they came to the Messenger of Allah and told him. He said to the one who had not repeated it: “You followed the Sunnah, and your prayer sufficed.” To the one who had performed ablution and repeated the prayer, he said: “You will have a double reward.”’ Abū Dāwūd and al-Dārimī transmitted it; al-Nasāʾī transmitted a similar report.

The same compiler and Abū Dāwūd also transmitted a disconnected (mursal) version from ʿAṭāʾ ibn Yasār.