عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ ((مَنِ اكْتَحَلَ فَلْيُوتِرْ وَمَنْ فَعَلَ فَقَدْ أَحْسَنَ وَمَنْ لَا فَلَا حَرَجَ عَلَيْهِ وَمَنِ اسْتَجْمَرَ فَلْيُوتِرْ وَمَنْ فَعَلَ فَقَدْ أَحْسَنَ وَمَنْ لَا فَلَا حَرَجَ وَمَنْ أَكَلَ فَمَا تَخَلَّلَ فَلْيَلْفِظْ وَمَنْ لَاكَ بِلِسَانِهِ فَلْيَبْتَلِعْ مَنْ فَعَلَ فَقَدْ أَحْسَنَ وَمَنْ لَا فَلَا حَرَجَ وَمَنْ أَتَى الْغَائِطَ فَلْيَسْتَتِرْ فَإِنْ لَمْ يَجِدْ إِلَّا أَنْ يَجْمَعَ كَثِيبًا فَلْيَسْتَدْبِرْهُ فَإِنَّ الشَّيْطَانَ يَلْعَبُ بِمَقَاعِدِ بَنِي آدَمَ مَنْ فَعَلَ فَقَدْ أَحْسَنَ وَمَنْ لَا فَلَا حَرَجَ))
Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: Whoever applies kohl, let him apply it in odd numbers; whoever does so has done a good deed, and whoever does not, there is no harm upon him. Whoever performs istinja (cleansing) with stones, let him use an odd number of stones; whoever does so has done a good deed, and whoever does not, there is no harm upon him. Similarly, whoever, after eating, removes food particles from his teeth, let him throw them away, and if he gathers food particles in his mouth with his tongue, let him swallow them; whoever does so has done a good deed, and whoever does not, there is no harm upon him. Whoever comes to relieve himself, let him cover himself; if he finds nothing to cover himself with, let him make a heap and turn his back towards it, for Satan plays with the private parts of the children of Adam; whoever does so has done a good deed, and whoever does not, there is no harm upon him.