"There are two things which I never asked anyone about after I saw the Messenger of Allah ﷺ. He was with us on a journey and he went away to relieve himself, then he came and performed Wudu', and he wiped over his forehead and two sides of his 'Imamah, and he wiped over his Khuffs." He said: "And (the other issue) the Imam's Salah behind one of his followers. I saw the Messenger of Allah ﷺ when he was on a journey and time for prayer came. The Prophet ﷺ could not join them, so they called the Iqamah and they asked Ibn 'Awf to lead them in prayer. Then the Messenger of Allah ﷺ came and offered the remainder of the prayer behinf Ibn 'Awf, then when Ibn 'Awf said the Salah, the Prophet ﷺ stood up and completed what he had missed (of the prayer)." (Using translation from Nasāʾī 109)  

خَصْلَتَانِ لَا أَسْأَلُ عَنْهُمَا أَحَدًا بَعْدَمَا شَهِدْتُ مِنْ رَسُولِ اللهِ ﷺ إِنَّا كُنَّا مَعَهُ فِي سَفَرٍ فَبَرَزَ لِحَاجَتِهِ ثُمَّ جَاءَ فَتَوَضَّأَ وَمَسَحَ بِنَاصِيَتِهِ وَجَانِبَيْ عِمَامَتِهِ وَمَسَحَ عَلَى خُفَّيْهِ قَالَ وَصَلَاةُ الْإِمَامِ خَلْفَ الرَّجُلِ مِنْ رَعِيَّتِهِ قَالَ فَشَهِدْتُ مِنْ رَسُولِ اللهِ ﷺ أَنَّهُ كَانَ فِي سَفَرٍ فَحَضَرَتِ الصَّلَاةُ فَاحْتَبَسَ عَلَيْهِمُ النَّبِيُّ ﷺ فَأَقَامُوا الصَّلَاةَ وَقَدَّمُوا ابْنَ عَوْفٍ فَصَلَّى بِهِمْ وَجَاءَ النَّبِيُّ ﷺ فَصَلَّى خَلْفَ ابْنِ عَوْفٍ مَا بَقِيَ مِنَ الصَّلَاةِ فَلَمَّا سَلَّمَ ابْنُ عَوْفٍ قَامَ النَّبِيُّ ﷺ فَقَضَى مَا سُبِقَ بِهِ