Sunan al-Nasa'i
The Book of Purification — Hadith #325
أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ الأَعْلَى، قَالَ حَدَّثَنَا أُمَيَّةُ بْنُ خَالِدٍ، قَالَ أَنْبَأَنَا شُعْبَةُ، أَنَّ مُخَارِقًا، أَخْبَرَهُمْ عَنْ طَارِقٍ، أَنَّ رَجُلاً، أَجْنَبَ فَلَمْ يُصَلِّ فَأَتَى النَّبِيَّ صلى الله عليه وسلم فَذَكَرَ ذَلِكَ لَهُ فَقَالَ " أَصَبْتَ " . فَأَجْنَبَ رَجُلٌ آخَرُ فَتَيَمَّمَ وَصَلَّى فَأَتَاهُ فَقَالَ نَحْوَ مَا قَالَ لِلآخَرِ يَعْنِي " أَصَبْتَ " .
“You did the right thing.” Another man became Junub and performed Tayammum and prayed, and he came to him and he said something similar to what he had told the other man – meaning, you did the right thing.
Chain of Narration (Isnad)