Mishkat al-Masabih 533, 534
Abu Sa’id al-Khudri said:
Two men went out on a journey, and when the time for prayer came, having no water with them, they performed ablution with good earth and then prayed. Immediately afterwards they found water, and one of them repeated the prayer with ablution, but the other did not. When they came to God’s messenger sometime afterwards they mentioned that, and he said to the one who did not repeat the prayer, "You have observed the sunna and your prayer was enough for you." To the one who had performed ablution and repeated the prayer he said, "You will have a twofold reward.” 

Abu Dawud and Darimi transmitted it, and Nasa’i transmitted something similar.
He and Abu Dawud also transmitted it from ‘Ata’ b. Yasar in mursal form.
وَعَن أبي سعيد الْخُدْرِيّ قَالَ: خَرَجَ رَجُلَانِ فِي سَفَرٍ فَحَضَرَتِ الصَّلَاةُ وَلَيْسَ مَعَهُمَا مَاءٌ فَتَيَمَّمَا صَعِيدًا طَيِّبًا فَصَلَّيَا ثُمَّ وَجَدَا الْمَاءَ فِي الْوَقْتِ فَأَعَادَ أَحَدُهُمَا الصَّلَاة وَالْوُضُوء وَلَمْ يَعُدِ الْآخَرُ ثُمَّ أَتَيَا رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فذكرا ذَلِك لَهُ فَقَالَ لِلَّذِي لَمْ يُعِدْ: «أَصَبْتَ السُّنَّةَ وَأَجْزَأَتْكَ صَلَاتُكَ» وَقَالَ لِلَّذِي تَوَضَّأَ وَأَعَادَ: «لَكَ الْأَجْرُ مَرَّتَيْنِ» . رَوَاهُ أَبُو دَاوُدَ وَالدَّارِمِيُّ وَرَوَى النَّسَائِيُّ نَحوه
وَقَدْ رَوَى هُوَ وَأَبُو دَاوُدَ أَيْضًا عَنْ عَطاء بن يسَار مُرْسلا