Al Istinja; refers to the method of cleansing najis from it’s exit point. It is a mandatory act ( wajib )
It is permissible to use mutlaq water as well as other means as long as it is solid and coarse such as stone, leaves and etc with the ability to rid of the najis.
According to the Shafi’i madhhab it is commendable to first use stone or the likes of it to remove najis followed by using mutlaq water since the stone or it’s like remove the ain of the najis whereas water removes it’s remnants.
But if you wish to choose only one method then water is the best solution since it removes both the substance and remnants
When using stone or it’s like, it’s is commendable to use it in odd numbers with at least three stones or three corners of the stone ( Sahih Imam Al Bukhari : 155 ) ( Sahih Imam Muslim: 2622 )
- It is not permissible to use najis or mutanajjis to cleanse oneself.
- It is haram to use edible items such as food eaten by man or bones which is the food of the jinns. ( Sahih Imam Muslim : 450, Sahih Tirmidhi: 18 )
- It is also haram to use body parts of animals still attached to it such as it’s feet or hand.
WalLahu Subhanahu wa Ta’ala a’lam.