To carry an 'Anaza (spear-headed stick) along with the water for washing the private parts after answering the call of nature. Sahih al-Bukhari 152
Arabic hadith text
حَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ، قَالَ حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ عَطَاءِ بْنِ أَبِي مَيْمُونَةَ، سَمِعَ أَنَسَ بْنَ مَالِكٍ، يَقُولُ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلميَدْخُلُ الْخَلاَءَ، فَأَحْمِلُ أَنَا وَغُلاَمٌ إِدَاوَةً مِنْ مَاءٍ، وَعَنَزَةً، يَسْتَنْجِي بِالْمَاءِ.تَابَعَهُ النَّضْرُ وَشَاذَانُ عَنْ شُعْبَةَ. الْعَنَزَةُ عَصًا عَلَيْهِ زُجٌّ
Translation
Narrated Anas bin Malik
Whenever Allah's Messenger (ﷺ) went to answer the call of nature, I along with another boy used to carry a tumbler full of water (for cleaning the private parts) and a short spear (or stick).