Getting water carried by somebody else for purification (washing one's private parts).

وَقَالَ أَبُو الدَّرْدَاءِ: أَلَيْسَ فِيكُمْ صَاحِبُ النَّعْلَيْنِ وَالطَّهُورِ وَالْوِسَادِ.And Abu Ad-Darda’ said (to the people of Iraq), “Is not the man whose nicknames are Sahib An-Na‘lain, Sahib At-Tahir, and Sahib Al-Wisad (‘Abdullah bin Mas‘ud) amongst you?” [‘Abdullah bin Mas‘ud used to carry the Na‘lain (shoes) and Tahir (water for purification and ablution) and Wisad (carpet) for the Prophet ﷺ, so he was called by those names]. ​​