إِبْرَاهِيمُ بْنُ جَرِيرٍ، عَنْ أَبِيهِ، أَنَّ نَبِيَّ اللَّهِ ـ صلى الله عليه وسلم ـ دَخَلَ الْغَيْضَةَ فَقَضَى حَاجَتَهُ فَأَتَاهُ جَرِيرٌ بِإِدَاوَةٍ مِنْ مَاءٍ فَاسْتَنْجَى مِنْهَا وَمَسَحَ يَدَهُ بِالتُّرَابِ
Ibrahim bin Jarir narrated from his father that:
The Prophet of Allah entered a thicket and relieved himself, then Jarir brought him a small water skin from which he cleansed himself, then he wiped his hand in the dirt.
[Saheeh Ibn Majah no. 293]
Shaikh Abdul-Muhsin al-‘Abbad hafidhuhallah was asked regarding this Hadith:
Does using soap takes its place?
Yes, as it is well-known it is recommended. It is not a must. Dirt becomes like soap in this time period.
[Sharh Sunan Ibn Majah no. 38]
Faisal Ibn Abdul Qaadir Ibn Hassan