The Prophet ﷺ said: If anyone applies collyrium, he should do it an odd number of times. If he does so, he has done well; but if not, there is no harm. If anyone cleanses himself with pebbles, he should use an odd number. If he does so, he has done well; but if not, there is no harm. If anyone eats, he should throw away what he removes with a toothpick and swallow what sticks to his tongue. If he does so, he has done well; if not, there is no harm. If anyone goes to relieve himself, he should conceal himself, and if all he can do is to collect a heap of send, he should sit with his back to it, for the devil makes sport with the posteriors of the children of Adam. If he does so, he has done well; but if not, there is no harm. (Using translation from Abū Dāʾūd 35)   

قَالَ رَسُولُ اللَّهِ ﷺ «مَنِ اكْتَحَلَ فَلْيُوتِرْ مَنْ فَعَلَ فَقَدْ أَحْسَنَ وَمَنْ لَا فَلَا حَرَجَ مَنِ اسْتَجْمَرَ فَلْيُوتِرْ مَنْ فَعَلَ فَقَدْ أَحْسَنَ وَمَنْ لَا فَلَا حَرَجَ مَنْ أَكَلَ فَلْيَتَخَلَّلْ فَمَا تَخَلَّلَ فَلْيَلْفِظْ وَمَا لَاكَ بِلِسَانِهِ فَلْيَبْتَلِعْ من فعل ذلك فقد أحسن ومن لا فلا حرج مَنْ أَتَى الْغَائِطَ فَلْيَسْتَتِرْ فَإِنْ لَمْ يَجِدْ إِلَّا كَثِيبَ رَمْلٍ فَلْيَسْتَدْبِرْهُ فَإِنَّ الشَّيَاطِينَ يَتَلَاعَبُونَ بِمَقَاعِدِ بَنِي آدَمَ مَنْ فَعَلَ فَقَدْ أَحْسَنَ وَمَنْ لَا فَلَا حَرَجَ»  

"The thing that the Prophet most liked to conceal himself behind when relieving himself was a hillock or a stand of date-palm trees." (Using translation from Ibn Mājah 340)  

«كَانَ أَحَبَّ مَا اسْتَتَرَ بِهِ النَّبِيُّ ﷺ لِحَاجَةٍ هَدَفٌ أَوْ حَائِشُ نَخْلٍ»