بسم الله الرحمن الرحيم

Anas bin Mālik narrated:
انَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَدْخُلُ الْخَلاَءَ فَأَحْمِلُ أَنَا وَغُلاَمٌ نَحْوِي إِدَاوَةً مِنْ مَاءٍ وَعَنَزَةً فَيَسْتَنْجِي بِالْمَاءِ
When the Messenger of Allāh (ﷺ) entered the khalā (i.e. privy), I and another boy like me (i.e. close in age) would carry a small water skin and a small spear. He would make istinjā – clean himself with water. (Sahīh Muslim 271)
Ibn Mulaqqin said:
The doctrine of the majority of the predecessors (salaf) and the successors (khalaf), and upon which the imāms of verdicts (fatwas) from the people of the regions agreed upon;
It is better to combine water and stone, to precede with stone and then use water – so that the impurity is reduced and touching (the impurity) with ones hand is lessened, and is better in cleanliness.
If one wants to limit himself to one of them, then water is better because it removes the impurity itself and its traces, and the stone removes the impurity itself but not the traces, but one is pardoned in their own right and prayer with it is valid as (the case) with other impurities.
(Al-‘Ilām Bi Fawāid ‘Umdatul-Ahkām 1/487)
