Accompanied by 'Abd Allah b. 'Umar, I went to Ibn 'Abbas for a certain work. He (Ibn 'Abbas) narrated a tradition saying: A man passed by the Messenger of Allah ﷺ in a street, while he returned from the toilet or just urinated. He (the man) saluted him, but the Prophet did not return the salutation. When the man was about to disappear (from sight) in the street he struck the wall with both his hands and wiped his face with them. He then struck another stroke and wipes his arms. He then returned the man's salutation. Then he said: I did not return the salutation to you because I was not purified. Abu Dawud said: I heard Ahmad b. Hanbal say: Muhammad b. Thabit reported a rejected tradition. Ibn Dasah said: Abu Dawud said: No one supported Muhammad b. Thabit in respect of narrating this tradition as to striking the wall twice (for wiping) from the Prophet ﷺ, but reported it as an action of Ibn 'Umar. (Using translation from Abū Dāʾūd 330)   

أَنْ قَالَ مَرَّ رَجُلٌ عَلَى رَسُولِ اللهِ ﷺ فِي سِكَّةٍ مِنَ السِّكَكِ وَقَدْ خَرَجَ مِنْ غَائِطٍ أَوْ بَوْلٍ فَسَلَّمَ عَلَيْهِ فَلَمْ يَرُدَّ عَلَيْهِ السَّلَامَ حَتَّى إِذَا كَادَ الرَّجُلُ أَنْ يَتَوَارَى مِنَ السِّكَّةِ ضَرَبَ بِيَدَيْهِ عَلَى الْحَائِطِ فَمَسَحَ وَجْهَهُ ثُمَّ ضَرَبَ بِيَدَيْهِ ضَرْبَةً أُخْرَى فَمَسَحَ ذِرَاعَيْهِ ثُمَّ رَدَّ عَلَى الرَّجُلِ السَّلَامَ وَقَالَ إِنَّهُ لَمْ يَمْنَعْنِي أَنْ أَرُدَّ عَلَيْكَ السَّلَامَ إِلَّا أَنِّي لَمْ أَكُنْ عَلَى طُهْرٍ لَفْظُ حَدِيثِ يَحْيَى بْنِ يَحْيَى وَهُوَ أَتَمُّهُمَا