Two persons set out on a journey. Meanwhile the time of prayer came and they had no water. They performed tayammum with clean earth and prayed. Later on they found water within the time of the prayer. One of them repeated the prayer and ablution but the other did not repeat. Then they came to the Messenger of Allah ﷺ and related the matter to him. Addressing himself to the one who did not repeat, he said: You followed the sunnah (model behavior of the Prophet) and your (first) prayer was enough for you. He said to the one who performed ablution and repeated: For you there is the double reward. Abu Dawud said: Besides Ibn Nafi' this is transmitted by al-Laith from 'Umairah b. Abi Najiyyah from Bakr b. Sawadah on the authority of 'Ata b. Yasar from the Prophet ﷺ. Abu Dawud said: The mention of (the name of the Companion) Abu Sa'id in this tradition is not guarded. This is a mural tradition (i.e. the Successor 'Ata b. Yasar directly narrates it from the Prophet, leaving the name of the Companion in the chain.)  

خَرَجَ رَجُلاَنِ فِي سَفَرٍ فَحَضَرَتِ الصَّلاَةُ وَلَيْسَ مَعَهُمَا مَاءٌ فَتَيَمَّمَا صَعِيدًا طَيِّبًا فَصَلَّيَا ثُمَّ وَجَدَا الْمَاءَ فِي الْوَقْتِ فَأَعَادَ أَحَدُهُمَا الصَّلاَةَ وَالْوُضُوءَ وَلَمْ يُعِدِ الآخَرُ ثُمَّ أَتَيَا رَسُولَ اللَّهِ ﷺ فَذَكَرَا ذَلِكَ لَهُ فَقَالَ لِلَّذِي لَمْ يُعِدْ أَصَبْتَ السُّنَّةَ وَأَجْزَأَتْكَ صَلاَتُكَ وَقَالَ لِلَّذِي تَوَضَّأَ وَأَعَادَ لَكَ الأَجْرُ مَرَّتَيْنِ  

Two persons from the Companions of the Messenger of Allah ﷺ; he then narrated the rest of the tradition to the same effect.  

أَنَّ رَجُلَيْنِ مِنْ أَصْحَابِ رَسُولِ اللَّهِ ﷺ بِمَعْنَاهُ